UNIT-I C Programming

UNIT-I
Introduction to Computer:
A Computer is an electronic device that takes data and instructions as an input from
the user, process data, and provides useful information known as output. This cycle of
operation of a computer is known as the input-process-output cycle.

Charles Babbage (26 December 1791 – 18

October 1871) was an English polymath.

He is known as father of computers.

Invented first analytical computer in year 1822.

 Data : Data is the collection of different types of entities (i.e A-Z,0-9, symbols and
character sets etc.) or the raw facts of a computers are called data.
 Information : The meaning full results occurred from data after performing process
on it.
 Process : The intermediate work performed between data and information is know
as process.

1.1 Computing Environments :

Computing Environment is a collection of computers / machines, software, and networks
that support the processing and exchange of electronic information meant to support
various types of computing solutions.

Types of Computing Environments Personal

 Personal Computing Environment. Cluster Time

 Time sharing Environment. Sharing
 Client Server Computing Environment.
 Distributed Computing Environment. Types of
 Cloud computing Environment. Computing
 Cluster computing Environment. Environment

Client
Cloud Server

Distribu
ted

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Personal Computing Environment:

In the personal computing environment, there is a single computer system. All the
system processes are available on the computer and executed there. The different devices
that constitute a personal computing environment are laptops, mobiles, printers, computer
systems, scanners etc.

Time Sharing Computing Environment :

The time sharing computing environment allows multiple users to share the system
simultaneously. The advantage of time sharing environment is multi programming and multi-
tasking at the same time. The users are connected to one or more computers.

Client-Server Computing Environment :

A client/server system is “a networked computing model that distributes processes between
clients and servers, which supply the requested service.” A client/server network connects
many computers called clients, to a main computer, called a server. Whenever client requests
for something, server receives the request and process it .

Distributed Computing Environment :

A Distributed Computing Environment Provides a seamless integration of computing
functions between different servers and clients. the servers are connected by internet all over
the world.

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Cloud Computing Environment : The computing is moved away from individual computer
systems to a cloud of computers in cloud computing environment. The cloud users only see the
service being provided and not the internal details of how the service is provided. This is done
by pooling all the computer resources and then managing them using a software.

Cluster Computing Environment : The clustered computing environment is similar to

parallel computing environment as they both have multiple CPUs. However a major difference
is that clustered systems are created by two or more individual computer systems merged
together which then work parallel to each other.

1.2 Computer Languages

A programming language: The language used in the communication of computer instructions
is known as the programming language. It is a formal constructed language designed to
communicate instructions to a machine, particularly a computer.
Programming languages can be used to create programs to control the behavior of a machine.

There are three levels of programming languages are available. They are:
1. Machine languages (Low-level Languages)
2. Assembly languages (Symbolic Languages)
3. High level languages

Machine Languages
A language that is directly understood by the computer without any translation is
called machine languages. A machine language is string of 0s and 1s. Machine language are
usually referred to as the first generation languages. It is also referred to as machine code or
object code. Therefore, all instructions and data should be written using binary codes i.e., 0’s
and 1’s.Each instruction performs a specific task, such as a load, a jump, or an ALU operation
on a unit of data in a CPU register or memory.

Machine language is the lowest-level programming language. Programs and applications

written in low-level language are directly executable on the computing hardware without any
interpretation or translation. Machine language and assembly language are popular examples
of low level languages.
An instruction written in any machine language has two parts:
i. Operation code (Opcode)
ii. Operand address or location

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Advantages:
 Execution speed is very fast
 Efficient use of primary memory
 It does not require any translation because machine code is directly understood by the
computer.

Disadvantages
 Machine dependent: The machine language is different for different types of
computers.
 Difficult to write program: because it requires memorizing dozens of opcodes for
different commands.
 Error prone: Difficult to modify

Assembly Languages: Assembly languages are usually referred to as the second-generation

languages. It is also lowest-level programming language. These are introduced in 1950’s.
 Assembly languages are just one level higher than machine language.
 Assembly language consists of special codes called mnemonics to represent the
language instructions instead of 0’s and 1’s. The mnemonic code is also called as
operation code or opcode.
For example, ADD, SUB, MUL, JMP, LOAD

Advantages
 Easier to memorize and use:Assembly language program is easy to use,
understand and memorize because it uses mnemonic codes in place of binary codes
 Easy to write input data: In assembly language programs the input data can be
written in decimal number system, later they are converted into binary.
 It is easier to correct errors and modify program instructions.
 The Assembly Language has the same efficiency of execution as the machine level
language. Because this is one-to-one translator between assembly language
program and its corresponding machine language program.
 Easy print out.
 Good library facility.

Disadvantages
 Machine dependent. A program written for one computer might not run in other
computers with different hardware configuration.
 Knowledge of hardware is required.
 Time consuming
 Translators required (i.e. Assembler)

Assembler: The software used to convert an assembly language programs into machines
codes is called an assembler.

High Level Languages: Sometimes abbreviated as HLL, a high-level language is a computer

programming language that isn't limited by the computer, designed for a specific job, and is
easier to understand. It is more like human language and less like machine language. However,
for a computer to understand and run a program created with a high-level language, it must be
compiled into machine language.
The first high-level languages were introduced in the 1950's. Today, there are many
high-level languages in use, including BASIC, C, C++, COBOL, FORTRAN, Java, Pascal,
Perl, PHP, Python, Ruby and Visual Basic.

High-level programming languages can be classified into the following three categories:

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1. Procedure-oriented languages (Third generation)

2. Problem-oriented languages (Fourth generation)
3. Natural languages (Fifth generation)

Procedure-oriented languages (Third generation)

A third generation (programming) language (3GL) is a grouping of programming
languages that introduced significant enhancements to second generation languages, primarily
intended to make the programming language more programmer-friendly.

English words are used to denote variables, programming structures and commands, and
Structured Programming is supported by most 3GLs. commonly known 3GLs are FORTRAN,
BASIC, Pascal and the C-family (C, C+, C++, C#, Objective-C) of languages.

Also known as 3rd generation language or a high-level programming language.

Problem-oriented languages (Fourth generation)
A fourth generation (programming) language (4GL) is a grouping of programming languages
that attempt to get closer than 3GLs to human language, form of thinking and
conceptualization.

4GLs are designed to reduce the overall time, effort and cost of software development. The
main domains and families of 4GLs are: database queries, report generators, data
manipulation, analysis and reporting, screen painters and generators, GUI creators,
mathematical optimization, web development and general purpose languages. also known as a
4th generation language, a domain specific language, or a high productivity language.

Natural Languages (Fifth Generation)

A fifth generation (programming) language (5GL) is a grouping of programming
languages build on the premise that a problem can be solved, and an application built to solve
it, by providing constraints to the program (constraint-based programming), rather than
specifying algorithmically how the problem is to be solved (imperative programming).

In essence, the programming language is used to denote the properties, or logic, of a

solution, rather than how it is reached. Most constraint-based and logic programming
languages are 5GLs. A common misconception about 5GLs pertains to the practice of some
4GL vendors to denote their products as 5GLs, when in essence the products are evolved and
enhanced 4GL tools. Also known as 5th generation languages.

Advantages:
 High-level languages are user-friendly
 They are easier to learn
 They are easier to maintain
 They are problem-oriented rather than 'machine'-based
 A program written in a high-level language can be translated into many machine
languages and can run on any computer for which there exists an appropriate translator
 The language is independent of the machine on which it is used i.e. programs
developed in a high-level language can be run on any computer text
 They are similar to English and use English vocabulary and well-known symbols
 A high-level language has to be translated into the machine language by a translator,
which takes up time
 The object code generated by a translator might be inefficient compared to an
equivalent assembly language program

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1.3 Problem Solving or Program Development Steps

Problem Solving is the process of solving a problem in a computer system by
following a sequence of steps.
1. Defining the problem.
2. Designing the algorithm.
3. Coding the program.
4. Testing and debugging the program.
5. Implementing the program.
6. Maintaining and updating the program.

Defining the problem

It involves recognizing the problem; identifying exactly what the problem is;
determining the available inputs and desired output; deciding whether problem can be solved
by using computer.

Designing the algorithm

An algorithm is finite set of step-by-step instructions that solve a problem. After
defining the problem, algorithm can designed.

Coding the program

It involves actually writing the instructions in a particular language that tell the
computer how to operate.

Testing and debugging the program

After coding, the program must be tested to ensure that is correct and contains no
errors. Three types of errors or bugs can be found which are
1. Syntax error
2. Logical error
3. Runtime error

Syntax Error
Syntax is a set of rules by which a programming language is governed. Syntax error
occurs when these rules are violated while coding of the program.

Logical Error
Improper coding of individual statements either or sequence of statements causes this
type of computer program. It does not stop the program execution but gives wrong results.

Runtime Error
This error in a computer program stops its execution. It may be caused by an entry of
invalid data.

Implementing the Program

After a program has been listed and debugged, it can be installed and implemented.
Maintaining and Upgrading the Program
After a program is developed and implemented can be upgraded as per the
requirements of the user. Maintaining and upgrading the program is an ongoing process

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1.4 Algorithm:
An algorithm is a finite set of step-by-step instructions to solve a problem. The
essential properties of an algorithm are:
1. Finiteness: The algorithm must always terminate after a finite number of steps.
2. Definiteness: Each and every instruction should be precise and unambiguous i.e. each
and every instruction should be clear and should have only one meaning.
3. Effectiveness: Each instruction should be performed in finite amount of time.
4. Input and Output: An algorithm must take zero or more inputs, and produce one or
more outputs.
5. Generality: An algorithm applies to different sets of same input type.

Advantages:
1. It is step-by-step solution to a given problem which is very easy to understand.
2. It has got a definite procedure.
3. It is easy to first develop an algorithm, then convert into a flowchart and then into a
computer program.
4. It is easy to debug as every step has got its own logical sequence.
5. It is independent of programming languages.

Disadvantages:
1. It is time consuming and cumbersome as an algorithm is developed first which is
converted into flowchart and then into a computer program
2. Algorithm lacks visual representation hence understanding the logic becomes
difficult.
Examples:
Write an algorithm to add two numbers
Step 1: Start
Step 2: Declare variables num1, num2 and sum
Step 3: Read num1 and num2
Step 4: Add num1 and num2 and assign the result to sum. sum←num1+num2
Step 5: Display sum
Step 6: Stop

Write an algorithm to find the largest among three different numbers

Step 1: Start
Step 2: Declare variables A, B and C.
Step 3: Read variables A, B and C.
Step 4: If A>B
If A>C
Display A is the largest number.
else
Display C is the largest number.
else
If B>C
Display B is the largest number.
Else
Display C is the largest number.
Step 5: Stop

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1.5 Flowchart
Flowchart is a pictorial or symbolic representation of an algorithm.It indicates process of
solution. They are constructed by using special geometrical symbols. Each symbol represents
an activity. Flowcharts are read from top to bottom unless a branch alters the normal flow.

Advantages
1. It clarifies the program logic.
2. Before coding begins the flowchart assists the programmer in determining the type of
logic control to be used in a program
3. The flowchart gives pictorial representation
4. Serves as documentation
5. Serves as a guide for program writing.
6. Ensure that all possible conditions are accounted for.
7. Help to detect deficiencies in the problem statement.

Disadvantages:
1. When the program logic is complex the flowchart quickly becomes complex and
clumsy and lacks the clarity of decision table.
2. It alterations and modifications are required, the flowchart may require re-drawing
completely.
3. As the flowchart symbols cannot be typed reproduction of flowcharts often a problem.
4. It is sometimes difficult for a business person or user to understand the logic depicted
in a flowchart.

Symbols used to draw flowcharts:

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Comparison between flow chart and algorithm

S.No. Algorithm Flowchart

1 An algorithm is a finite set of step-
by-step instructions that solve Flowchart is a pictorial or symbolic
problem. representation of an algorithm.
2. Algorithm gives verbal which is Gives pictorial representation.
almost similar to English.
3. Suitable for large and modular Suitable for small programs
programs
4. Easier to understand To understand flowcharts one has to familiar
with symbols
5. Drawing tools are not required Required.

6. Algorithm can be typed. So Flowchart cannot typed so, reproduction is

reproduction is easy. problem.

Example for a flowchart

Pseudo code: It is a simple way of writing programming code in English. It is a combination

of generic syntax and normal English language. Pseudo code is not actual programming
language. It uses short phrases to write code for programs before actually create it in a
specific language.
It helps the programmer understand the basic logic of the program.

The example of a pseudo code to add two numbers and display the result as shown below:

DEFINE: Integer num1, num2, result

READ: Integer num1
READ: Integer num2
SET: result=num1+num2
Display: result

Advantages
 Developing program code using Pseudo codeis easier.
 The program code instructions are easier to modify in comparison to a flowchart.
 It is well suited for large program design.
Disadvantages

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 It is difficult to understand the program logic since it does not use pictorial
representation.
 There is no standard format for developing a Pseudocode

1.6 Frequently used software components in C:

Editor
In general, an editor refers to any program capable of editing files. The term editor is
commonly used to refer to a text editor, which is a software program that allows users to create
or manipulate plain text computer files or C source code. For example gedit, notepad,
WordPad etc.,

Debugger
This program helps us identify syntax errors in the source code.
Pre Processer
There are certain special instructions within the source code identified by the # symbol
that are carried on by a special program called a preprocessor.
Compiler
It is a program which translates a high level language program into a machine language
program.

Interpreter
An Interpreter is a program which translates statements of a program into machine code. It
translates only one statement of the program at a time.

Linker
The machine code relating to the source code you have written is combined with
some other machine code to derive the complete program in an executable file. This is done
by a program called the linker.
Loader
Loader is a program that loads machine codes of a program into the system memory.
In Computing, a loader is the part of an Operating System that is responsible for loading
programs.

Difference between Compiler and Interpreter

S.No. Compiler Interpreter

1 Compiler takes entire program as a Interpreter takes single instruction as input.
input.
2. Intermediate object code is generate. No Intermediate object code is generated.

3. Conditional control statements are Conditional control statements are executes

executes faster. faster.
4. Memory required is more. Memory required is less
(since object code is generated)
5. At a time higher level program is Every time higher level program is
converted into lower level. converted into lower level.

6. Errors are displayed after entire Errors are displayed every instruction
program is checked. Eg: C compiler interpreted. Eg: BASIC

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1.7 Introduction to C Language

C language was developed Dennis Ritchie in 1972 at AT&T Bell Laboratories (USA).
C language was derived from B language which was developed by Ken Thomson in 1970. This
B language was adopted from a language BCPL (Basic Combined Programming Language),
which was developed by Martin Richards at Cambridge University. The language B named as
so by borrowing the first initial from BCPL language. Dennis Ritchie modified and improved
B language and named it as C language, using second initial from BCPL.

C language is not high level language and not a low level language. It is a middle level
language with high level and low level features.

C is a general purpose, structured programming language. C language is one of the

most popular computer languages today because it is a structured, high level, machine
independent language. It allows software developers to develop software without worrying
about the hardware platforms where they will be implemented.

The following flowchart shows the history of ANSI C.

Fig: Taxonomy of C language

Here are most common reasons why C is still so popular:

 C is one of the most popular programming languages of all time to create system
software as well as application software.
 C is a standardized programming language with international standards.
 C is the base for almost all popular programming languages.
 C is one of the foundations for modern computer science and information technology.

Importance of C
It is a robust language whose rich set of built in functions and operators can be used to
write any complex program. The C compiler combines the capabilities of an assembly

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language with the features of a higher level language and therefore it is well suited for both
system software and business packages.
Features
 C is a general purpose language
 C can be used for system programming as well as application programming.
 C is middle level language
 C is portable language
 An application program written on C language will work on many different computers
with little or no modifications.
 C Block structured language. In C , a block is marked by two curly braces({ })
 C programs are compact, fast and efficient
 C is case sensitive language
 C is function oriented language
 C language includes advanced data types like pointers, structures, unions, enumerated
types etc.
 C language supports recursion and dynamic storage allocation
 C can manipulate with bits, bytes and addresses
 Parameter passing can be done using call-by-value and call-by-reference

Why Use c?
 Powerful and flexible
C is a powerful and flexible language. The language itself places no constraints on you.
C is used for projects as diverse as operating systems, Word Processors, graphics,
spreadsheets, and even compilers for other languages.
 Popular
C is a popular language preferred by professional programmers. As a result, a wide
variety of C compilers and helpful accessories are available for use by programmers.
 Portable
C is a portable language. Portable means that a C program written for one computer
system (say an IBM PC) can be compiled and run on another system (say a DEC VAX
system) with little or no modification. Portability is enhanced by the ANSI standard for
C, the set of rules for C compilers.
 Minimum keywords
C is a language of few words, containing only a handful of terms, called keywords,
which serve as the base on which the language's functionality is built. There is a
misconception with many that a language with more key words (sometimes called
reserved words) would be more powerful. This isn't true.
 Modular
C is a modular. C code can (and should) be written in routines called functions. These
functions can be reused in other applications or programs. By passing pieces of
information to the functions, you can create useful, reusable code.

1.7.1 The C Character Set

We know that English language has 26 alphabets. We will use combinations of these
alphabets to form words, sentences, paragraphs etc. In a similar way we will use the available
characters while writing programs in any programming language.

There are two set of characters in “C” language

 Source characters
 Execution characters

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Source Characters
These are characters that are used to create source text file. Source characters include

Alphabets A to Z, a to z
Digits 0,1,2,3,4,5,6,7,8,9
Special Characters , . ; : ? ‘ “ ! | / \ ~ _ $ % # & ^ * + - <> ( ) { } [ ] and blank

Execution Characters
The meaning of these characters is interpreted at the time of execution. These are also
known as “Escape sequences because the backslash (\) is considered as an ‘escape’ character.
It causes an escape from normal interpretation of a string. so that the next character is
recognized as one having special meaning.
Escape sequences
Escape
Meaning Result
Sequence
Moves the cursor to the previous position of the current
Backspace Line
\b

\a Bell(alert) Produces a beep sound for alert

\r Carriage return Moves the cursor to beginning of the current line.
\n New line Moves the cursor to beginning of the next line.
\0 Null Null character
\v Vertical tab Moves the cursor to next vertical tab position.
\t Horizontal tab Moves the cursor to next horizontal tab position.
\\ Backslash Present a character with backslash(\)
Comments
 Comments are used by programmers to add remarks and explanations within the
program.
 Compiler ignores all the comments and they do not have any effect on the executable
program.
 Comments are of two types; single line comments and multi-line comments.
 Single line comments start with two slashes ( // ) and all the text until the end of the line
is considered a comment.
// this is a single line comment

 Multi-line comments start with characters /* and end with characters */. Any text
between those characters is considered a multi-line comment.

/* this is a multi-line comment and

Welcome Rgukt */

1.8 Various kinds of C Data (Tokens):

The data in C language can be divided into

1. Constants/literals
2. Variables/Identifiers
3. Reserved Words/Key words
4. Delimiters

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1. Constants:
Constant can be defined as a value that can be stored in memory and cannot be
changed during execution of the program. Constants are used to define fixed values like pi. C
has four basic types of constants. They are:

Integer Constant
An integer constant must have at least one digit and should not have a decimal point. It can be
either positive or negative.
Examples for integer constants
1 9 234 999
Floating point Constant
A floating point constant is decimal number that contains either a decimal point or an
exponent. In the other words, they can be written in 2 forms: fractional and exponential.
When expressed in fractional form, note the following points.
1. There should be at least one digit, and could be either positive or negative value. A
decimal point is must.
2. There should be no commas or blanks.
Examples for fractional form
12.33 -19.56 +123.89 -0.7
When expressed in exponential form, a floating point constant will have 2 parts. One is before
e and after it. The part which appears before e is known as mantissa and the one which follows
is known as exponent. When expressed in this format, note the following points.
1. mantissa and exponential should be separated by letter E.
2. mantissa can have a positive and negative sign.
3. default is positive.

Examples for fractional form

2E-10 0.5e2 1.2E+3 -5.6E-2

Character Constant
These are single character enclosed in single quotes. A character can be single
alphabet, single digit, single special symbol enclosed with in single quotes. Not more than a
single character is allowed.
Example
‘a’ ‘Z’ ‘5’ ‘$’

String Constant
A String constant is sequence of characters enclosed in double quotes. So “a” is not
same as ‘a’. The characters comprising the string constant are stored in successive memory
locations.
Example: “hello” “programming” “cse”

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2. Variables/Identifiers
Variable is named memory location that can be used to store values. These variables
can take different values but one value at a time. These values can be changed during
execution of a program.
Identifiers are basically names given to program elements such as variables, arrays and
functions.

Rules for naming a Variable/Identifier

1. The only characters allowed are alphabets, digits and underscore (_).
2. They must start with an alphabet or an underscore (_).
3. It can not include any special characters or punctuation marks (like #, $, ^, ?, ., etc.)
except underscore (_).
4. They can be of any reasonable length. They should not contain more than 31
characters. But it is preferable to use 8 characters.
5. There cannot be two successive underscores.
6. Reserved words/keywords cannot be identifiers.
7. Lower case or uppercase letters are significant.

3. Key words:
 These are also called as reserved words.
 All Keywords have fixed meanings and these meanings cannot be changed.
 There are 32 keywords in C programming.
 Keywords serve as basic building blocks for a program statement.
 All keywords must be written in lowercase only.

ANSI C Keywords
Auto double Int struct
Break else Long switch
Case enum Register typedef
Char extern Return union
Const float Short unsigned
Continue for Signed void
Default goto Sizeof volatile
Do if Static while

4. Delimiters
Delimiters are used for syntactic meaning in C. These are given below:

Symbol Name Meaning

: Colon Used for label
; Semicolon End of statement
() Parenthesis Used in expression
[] Square brackets Used in expression
{} Curly braces Used for block of statements
# Hash Pre-processor directive
, Comma Variable separator

1.9 Variables Declaration & Initialization in C :

A variable is named memory location that stores a value. When using a variable, we
actually refer to address of the memory where the data is stored. C language supports two basic
kinds of variables:
1. Numeric variables

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2. Character variables

Numeric variables
Numeric variables can be used to store either integer values or floating point values.
While an integer value is a whole number without a fraction part or decimal point. A floating
point value can have a decimal point.

Numeric values may be associated with modifiers like short, long, signed, and
unsigned.

Character variables
Character variables can include any letter from the alphabet or from ASCII chart and numbers
0-9 that are given within single quotes.

Variable declaration
To declare a variable, specify the data type of the variable followed by its name. The
data type indicates the kind of data that the variable will store. Variable names should always
be meaningful and must reflect the purpose of their usage in the program. In C, variable
declaration always ends with a semicolon, for example:

char grade;
int emp_no;
float salary;
double bal_amount
unsigned short int acc_no;

C allows multiple variable of same type to be declared in one statement, so the following
statement is absolutely legal in C
float temp_in_deg, temp_in_farh;

Initializing variables
Assigning value to variable is called variable initialization. For example:
char grade= ‘A’;
int emp_no=1007;
float salary=8750.25;
double bal_amount=100000000

Note: When variables are declared but not initialized they usually contain garbage values.

Basically variable declaration can be done in three different places in a C program.

1. Inside main() function are called local variables.
2. Outside main() function are called global variables.
3. In the function definition header are called formal parameters.

Declaring Constants
To declare a constant, precede the normal variable declaration with const keyword and
assign it a value. For example,
const float pi=3.1415;
This const keyword specifies that the value of cannot change.

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1.10 Data Types of C :
C supports different types of data. The type or Data type refers a type of data that
is going to be stored in variable. Data types can be broadly classified as shown in figure.

C provides a standard minimal set of data types. Sometimes these are also called as ‘Primitive
types’. They are:
 ‘char’ is used to store any single character.
 ‘int’ is used to store integer value.
 ‘float’ is used to store floating point value
 ‘double’ is used for storing long range of floating point number.

Type Qualifiers
In addition, C has four type qualifiers, also known as type modifiers which precede the basic
data type. A type modifier alters the meaning of basic data type to yield a new data type. They
are as follows:
 Short
 long ( to increase the size of an int or double type)
 signed
 unsigned

The qualifiers can be classified into two types:

1. Size qualifier (e.g., short and long)
2. Sign qualifier (e.g., signed and unsigned)

Size qualifiers: alters the size of basic data type. The keywords long and short are two size
qualifiers. For example:
long int i;
The size of int is 2 bytes but, when long keyword is used, that variable will be either 4 bytes or
8 bytes.

Sign qualifiers: Whether a variable can hold only positive value or both values is specified by
sign qualifiers. Keywords signed and unsigned are used for sign qualifiers.

a. Each of these type modifiers can be applied to base type int.

b. The modifiers signed and unsigned can also be applied to base type char.
c. In addition long can also be applied to double.
d. When base type is omitted from a declaration, int is assumed.

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Example
Suppose a variable can be assigned only an integer value. Such variable can be declared as
int a;
This declaration reserves two bytes of memory for storing the number. Such a variable can
store a number in range -32768 to 32767. In order to increase the range you can add a qualifier
to the declaration.
long int a;
The following table shows the basic data types with qualifiers and their ranges.

Data Type Size (in Bytes) Range

Char 1 -128 to 127
unsigned char 1 0 to 255
signed char 1 -128 to 127
Int 2 -32768 to 32767
unsigned int 2 0 to 65535
signed int 2 -32768 to 32767
short int 2 -32768 to 32767
unsigned short int 2 0 to 65535
signed short int 2 -32768 to 32767
long int 4 -2147483648 to 2147483647
unsigned long int 4 0 to 4294967295
signed long int 4 -2147483648 to 2147483647
Float 4 3.4E-38 to 3.4E +38
Double 8 1.7E-308 to 1.7E+308
long double 10 3.4E-4932 to 1.1E+4932

void type
This type holds no value and thus valueless. It is primarily used in three cases:
1. To specify the return type of a function (when the function returns no value)
2. To specify the parameters of the function (when the function accepts no arguments
from the caller.
3. To create generic pointers.

1.11 Structure of a C Program

C program is a collection of one or more functions. Every function is collection of
statements, performs a specific task. The structure of a basic C program is:

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Documentation section
The documentation section consists of a set of comment lines giving the name of the
program, the author and other details, which the programmer would like to use later. There are
two types of comment lines.
1. Block comment lines /* */ and
2. Single line comment lines. //

Link section
The link section provides instructions to the compiler to link functions from the system
library.

#include directive
The #include directive instructs the compiler to include the contents of the file
"stdio.h" (standard input output header file) enclosed within angular brackets.

Definition section
The definition section defines all symbolic constants. #define PI 3.1413

Global declaration section

There are some variables that are used in more than one function. Such variables are
called global variables and are declared in the global declaration section that is outside of all
the functions. This section also declares all the user-defined functions.

main() function section

Every C program must have one main function section. This section contains two
parts:
1. Declaration part and
2. Executable part
Declaration part: It declares all the variables used in the executable part.

Executable part: There is at least one statement in the executable part.

These two parts must appear between the opening and closing braces. The program
execution begins at the opening brace and ends at the closing brace. The closing brace of the
main function is the logical end of the program. All statements in the declaration and
executable part end with a semicolon.

Subprogram section
The subprogram section contains all the user-defined functions that are called in the
main () function. User-defined functions are generally placed immediately after the main ()
function, although they may appear in any order.
For Example a ‘C’ program that prints welcome message:
#include<stdio.h>
int main( )
{
printf(“Welcome to C Programming\n”);
return 0;
}
Output
Welcome to C Programming.

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1.12 Formatted input and output functions:

When input and output is required in a specified format the standard
library functions scanf() and printf() are used

Output function printf( )

printf() is a function that is used to print any data on the video monitor screen. It has the
following form:
printf(“control string”,list_of_variables);
The function accepts two arguments - control string, which controls what gets printed, and list
of variables.
 The control string is all-important because it specifies
 The type of each variable in the list and how user wants it printed. It is also
called as format specifier.
 Characters that are simply printed as they are.
 Control string that begins with a % sign.
 Escape sequences that begin with a \ sign
 List of variables must be separate by comma.
 The number of format specifiers must exactly match the number of variables.

Format specifiers
Format
Data Type Display
specifier
%c Char Single character
%c unsigned char
%s Sequence of characters (String)
Int Signed integer (both +ve and –ve
%d values)
%u unsigned int Unsigned integer (only +ve values)
%hd short int Signed short integer
%ld long int Long integer
unsigned long Unsigned long integer (only +ve
%lu
Int values)
%o Int Octal values
%x Int Hexa decimal values
%f Float Floating-point value
Long Double precision floating-point
%lf
float/double value
long double Double precision floating-point
%Lf
value
%p pointer Address stored in pointer
%% None Prints %

Flag characters used in printf :

Flag Meaning
-- Left justify the display
+ Display the positive sign of value
0 Pad with leading zeros
space Display space if there is no sign

The simplest printf statement is

printf(“Welcome to the world of C language”);
When executed, it prints the string enclosed in double quotes on screen.

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Examples:
printf(“Result:%d%c%f\n”,12,’a’,2.3);
Result:12a2.3

printf(“Result:%d\t%c\t%f\n”,12,’a’,2.3);
Result:12 A 2.3
printf(“%6d\n”,1234);
1 2 3 4

printf(“%06d\n”,1234);
0 0 1 2 3 4

printf(“%-6d\n”,1234);
1 2 3 4

printf(“%-06d\n”,1234);
- 0 1 2 3 4

printf(“%2d\n”,1234);
1 2 3 4

printf(“%9.2f\n”,123.456);
1 2 3 . 4 6

char ch=’A’;
printf(“%c\n%2c\n%3c\n”,ch,ch,ch);
A
A
A

printf(“%X\n”,255);
FF

Input function scanf()

C provides scanf( ) function for entering input data. This function accepts all types of data as
input (numeric, character, string). The general form of scanf() is given below

Syntax
scanf(“control string”,variable1,variable2,…,variable n);

This function should have at least two parameters. First parameter is control string which is
conversion specification character. It should be within double quotes. This may be one or
more, it depends on the number of variables. The other parameter is variable names.
Each variable must preceded by ampersand (&) sign. This gives starting address of the
variable name in memory. scanf ( ) uses all the format specifiers used in printf( ) function.
Note: comments are not allowed in scanf()
For example, consider the following simple programs.
#include <stdio.h>
int main()
{
int x;
printf(“Enter number:”);
scanf(“%d”, &x);
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printf(“The value of x is %d\n”, x);

return 0;
}
Output
Enter a number: 45
The value of x is 45
For accessing multiple values from keyboard using scanf() function
#include <stdio.h>
int main()
{
int x,y;
printf(“Enter two numbere:”);
scanf(“%d%d”, &x,&y);
printf(“The value of x is %d\n”, x);
printf(“The value of y is %d\n”, y);
return 0;
}
Output
Enter two numbers: 29 47
The value of x is 29
The value of x is 47

1.13 Operators in C :
An operator is defined as a symbol that operates on operands and does
something. The something may be mathematical, relational or logical operation. C language
supports a lot of operators to be used in expressions. These operators can be categorized into
the following groups:
1. Arithmetic operators
2. Relational operators
3. Logical operators
4. Increment/Decrement operators
5. Bitwise operators
6. Conditional operators
7. Assignment operators
8. Special operators
Arithmetic operators
 These are used to perform mathematical operations.
 These are binary operators since they operate on two operands at a time.
 They can be applied to any integers, floating-point number or characters.
 C supports 5 arithmetic operators. They are +, -, *, /, %.
 The modulo (%) operator can only be applied to integer operands and cannot be used
on float or double values.
Consider three variables declared as,
int a=9,b=3,result;
We will use these variables to explain arithmetic operators. The table shows the arithmetic
operators, their syntax, and usage in C language.

Operation Operator Syntax Statement Result

Addition + a+b result=a+b 12
Subtraction - a-b result=a-b 6
Multiply * a*b result=a*b 27
Divide / a/b result=a/b 3
Modulo % a%b result=a%b 0

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a and b are called operands.
An Example ‘C’ program that illustrates the usage of arithmetic operators.

#include<stdio.h>
int main()
{
int a=9,b=3;
printf("%d+%d=%d\n",a,b,a+b);
printf("%d-%d=%d\n",a,b,a-b);
printf("%d*%d=%d\n",a,b,a*b);
printf("%d/%d=%d\n",a,b,a/b);
printf("%d%%%d=%d\n",a,b,a%b);
return 0;
}
Output
9+3=12
9-3=6
9*3=27
9/3=3
9%3=0

Relational operators
A relational operator, also known as a comparison operator, is an operator that
compares two operands. The operands can be variables, constants or expressions. Relational
operators always return either true or false depending on whether the conditional relationship
between the two operands holds or not.
C has six relational operators. The following table shows these operators along with their
meanings

Operator Meaning Example

< Less than 3<5 gives 1
> Greater than 7<9 gives 0
<= Less than or equal to 100<=100 gives 1
>= Greater than or equal to 50>=100 gives 0
== Equal to 10==9 gives 0
!= Not equal to 10!=9 gives 1

An example program that illustrates the use of arithmetic operators.

#include<stdio.h>
int main()
{
int a=9,b=3;
printf("%d>%d=%d\n",a,b,a>b);
printf("%d>=%d=%d\n",a,b,a>=b);
printf("%d<%d=%d\n",a,b,a<b);
printf("%d<=%d=%d\n",a,b,a<=b);
printf("%d==%d=%d\n",a,b,a==b);
printf("%d!=%d=%d\n",a,b,a!=b);
return 0;
}

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Output
9>3=1
9 >= 3 = 1
9<3=0
9 <= 3 = 0
9= =3 = 0
9 != 3 = 1
Logical operators
Operators which are used to combine two or more relational expressions are known as
logical operators. C language supports three logical operators – logical AND(&&), logical
OR(||), logical NOT( !).

Logical&& and logical || are binary operators whereas logical ! is an unary
operator.

All of these operators when applied to expressions yield either integer value 0
(false) or an integer value 1(true).

Logical AND
It is used to simultaneously evaluate two conditions or expressions with relational
operators. If expressions on the both sides (left and right side) of logical operators is true then
the whole expression is true otherwise false. The truth table of logical AND operator is given
below:

A B A&&B
0 0 0
0 1 0
1 0 0
1 1 1

Logical OR
It is used to simultaneously evaluate two conditions or expressions with relational
operators. If one or both the expressions on the left side and right side of logical operators is
true then the whole expression is true otherwise false. The truth table of logical OR operator is
given below:

A B A||B
0 0 0
0 1 1
1 0 1
1 1 1

Logical NOT
It takes single expression and negates the value of expression. The truth table of logical NOT
operator is given below

A !A
0 1
1 0

For example: x and y are two variables. The following equations explain the use of logical
operators.
z1 = x&&y …1
z2 = x||y …2
z3 =!x …3

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Equation1 indicates that z1 is true if both x and y is true. Equation2 indicates z2 is true when x
or y or both true. Equation3 indicates z3 is true when x is not true.

An example ‘C’ program that illustrates the use of logical operators

#include<stdio.h>
int main()
{
int z1,z2,z3;
z1=7>5 && 10>15;
z2=7>5 || 10>15;
z3=!(7>5);
printf(" z1=%d\n z2=%d\n z3=%d\n",z1,z2,z3);
return 0;
}
Output
z1=0
z2=1
z3=0

Unary operators
Unary operators act on single operands. C language supports three unary operators. They are:
1. Unary minus
2. Increment operator
3. Decrement operator

Unary minus
The unary minus operator returns the operand multiplied by –1, effectively changing its
sign. When an operand is preceded by a minus sign, the unary minus operator negates its value.
For example,
int a, b=10;
a=-(b);
the result of this expression is a=-10.

Increment (++) and decrement (− −) operators

The increment operator is unary operator that increases value of its operand by 1.
Similarly, the decrement operator decreases value of its operand by 1. These operators are
unique in that they work only on variables not on constants. These are used in loops like while,
do-while and for statements.
There are two ways to use increment or decrement operators in expressions. If you put
the operator in front of the operand (prefix), it returns the new value of the operand
(incremented or decremented). If you put the operator after the operand (postfix), it returns the
original value of the operand (before the increment or decrement).

Operator Name Value returned Effect on variable

x++ Post-increment X Incremented
++x Pre-increment x=x+1 Incremented
x− − Post-decrement X Decremented
− −x Pre-decrement x=x – 1 Decremented

An example program that illustrates the use of unary operators

#include<stdio.h>
int main()
{
int x=5;

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printf("x=%d\n", x++);
printf("x=%d\n",++x);
printf("x=%d\n",x--);
printf("x=%d\n",--x);
printf("x=%d\n",-x);
return 0;
}
Output
x=5
x=7
x=7
x=5
x=-5

Bitwise operators
As the name suggests, the bitwise operators operate on bits. These operations include:
1. bitwise AND(&)
2. bitwise OR(|)
3. bitwise X-OR(^)
4. bitwise NOT(~)
5. shift left(<<)
6. shift right(>>)

Bitwise AND (&)

When we use the bitwise AND operator, the bit in the first operand is ANDed with the
corresponding bit in the second operand. If both bits are 1, the corresponding bit in the result is
1 and 0 otherwise. For example:
In a C program, the & operator is used as follows.
int a=6,b=9,c;
c=a&b;
printf(“%d”,c); //prints 0

0110 (binary equivalent of decimal 6)

1001 (binary equivalent of decimal 9)
0000
Bitwise OR (|)
When we use the bitwise OR operator, the bit in the first operand is ORed with the
corresponding bit in the second operand. If one or both bits are 1, the corresponding bit in the
result is 1 and 0 otherwise. For example:
In a C program, the | operator is used as follows.
int a=4,b=2,c;
c=a|b;
printf(“%d”,c); //prints 6

100 (binary equivalent of decimal 4)

| 010 (binary equivalent of decimal 2)
110

Bitwise XOR (^)

When we use the bitwise XOR operator, the bit in the first operand is XORed with the
corresponding bit in the second operand. If both bits are different, the corresponding bit in the
result is 1 and 0 otherwise. The truth table operator is shown below:

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A B A^B
0 0 0
0 1 1
1 0 1
1 1 0

For example:
In a C program, the | operator is used as follows.
int a=4,b=2,c;
c=a^b;
printf(“%d”,c); //prints 6

100 (binary equivalent of decimal 4)

|010 (binary equivalent of decimal 2)
110

Bitwise NOT (~)

One’s complement operator (Bitwise NOT) is used to convert each 1 to 0 and 0 to 1, in
the given binary pattern. It is a unary operator i.e. it takes only one operand.

For example, In a C program, the ~ operator is used as follows.

int a=4,c;
c=~a;
printf(“%d”,c); //prints -5

~100 (binary equivalent of decimal 4)

101

Shift operators
C supports two bitwise shift operators. They are shift-left (<<) and shift-right (>>).
These operations are simple and are responsible for shifting bits either to left or to the right.
The syntax for shift operation can be given as:

operand operator num

where the bits in operand are shifted left or right depending on the operator (<<, >>) by the
number of places denoted by num.

Left shift operator

When we apply left-shift, every bit in x is shifted to left by one place. So, the MSB
(Most Significant Bit) of x is lost, the LSB (Least Significant Bit) of x is set to 0.

Let us consider int x=4;

Now shifting the bits towards left for 1 time, will give the following result
MSB LSB
3 2 1 0
2 2 2 2
8 4 2 1
x=4 0 1 0 0
1 0 0
x<<1 = 1 0 0 0 the result of x<<1 is 8

Left-shift is equals to multiplication by 2.

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Right shift operator

When we apply right-shift, every bit in x is shifted to right by one place. So, the LSB
(Least Significant Bit) of x is lost, the MSB (Most Significant Bit) of x is set to 0. Let us
consider int x=4;
Now shifting the bits towards right for 1 time, will give the following result.
3 2 1 0
2 2 2 2
8 4 2 1
x=4 0 1 0 0
0 1 0
x>>1 = 0 0 1 0 the result of x>>1 is 2

Right-shift is equals to division by 2.

An example ‘C’ program that illustrates the use of bitwise operators

#include <stdio.h>
int main()
{
int a=4,b=2;
printf("%d | %d = %d\n",a,b,a|b);
printf("%d & %d = %d\n",a,b,a&b);
printf("%d ^ %d = %d\n",a,b,a^b);
printf("~%d = %d\n",a,~a);
printf("%d<<1 = %d\n",a,a<<1);
printf("%d>>1 = %d\n",a,a>>1);
return 0;
}
Output:
4|2=6
4&2=0
4^2=6
~4 = -5
4 << 1 = 8
4 >> 1 = 2

Assignment operators
Assignment operator (=)
In C, the assignment operator (=) is responsible for assigning values to variables. When
equal sign is encountered in in an expression, the compiler processes the statement on the right
side of the sign and assigns the result to variable on the left side. For example,

int x;
x=10;
Assigns the value 10 to variable x. if we have,
int x=2,y=3,sum=0;
sum = x + y;
then sum=5.
The assignment has right-to-left associativity, so the expression
int a=b=c=10;
is evaluated as
(a=(b=(c=10)))

Consider the following set of examples:

a = 5; // value of variable ‘a’ becomes 5

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a = 5+10; // value of variable ‘a’ becomes 15

a = 5 + b; // value of variable ‘a’ becomes 5 + value of b
a = b + c; // value of variable ‘a’ becomes value of b + value of c

Short hand/Compound assignment operators

The assignment operator can be combined with the major arithmetic operators such
operators are called compound assignment operators. C language supports a set of
compound assignment operators of the form:
variable op = expression;
where op is binary arithmetic operator.

The following table lists the assignment operators supported by the C:

Op Description Example
Add AND assignment operator. It adds the right C += A is equivalent to
+= operand to the left operand and assign the result to C = C + A
the left operand.
Subtract AND assignment operator. It subtracts the C −= A is equivalent to
−= right operand from the left operand and assigns the C = C − A
result to the left operand.
Multiply AND assignment operator. It multiplies C *= A is equivalent to
*= the right operand with the left operand and assigns C = C * A
the result to the left operand.
Divide AND assignment operator. It divides the C /= A is equivalent to
/= left operand with the right operand and assigns the C = C / A
result to the left operand.
Modulus AND assignment operator. It takes C %= A is equivalent to
%= modulus using two operands and assigns the result C = C % A
to the left operand.
<<= Left shift AND assignment operator. C <<= 2 is same as C = C << 2
>>= Right shift AND assignment operator. C >>= 2 is same as C = C >> 2
&= Bitwise AND assignment operator. C &= 2 is same as C = C & 2
^= Bitwise exclusive OR and assignment operator. C ^= 2 is same as C = C ^ 2
|= Bitwise inclusive OR and assignment operator. C |= 2 is same as C = C | 2

An example ‘C’ program that illustrates the use of assignment operators

#include <stdio.h>
int main()
{
int a = 21,c;
c = a;
printf("Operator is = and c = %d\n", c ); c += a;
printf("Operator is += and c=%d\n",c); c −= a;
printf("Operator is −= and c=%d\n",c); c *= a;
printf("Operator is *= and c=%d\n",c); c /= a;
printf("Operator is /= and c=%d\n", c);
iii. = 200; c %= a;
printf("Operator is %= and c=%d\n",c); c <<= 2;
printf("Operator is <<= and c=%d\n",c);
c >>= 2;
printf("Operator is >>= and c=%d\n",c);
c &= 2;

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printf("Operator is &= and c = %d\n", c );

c ^= 2;
printf("Operator is ^= and c = %d\n", c );
c |= 2;
printf("Operator is |= and c = %d\n", c );
return 0;
}

Output
Operator is = and c = 21
Operator is += and c = 42
Operator is −= and c = 21
Operator is *= and c = 441
Operator is /= and c = 21
Operator is %= and c = 11
Operator is <<= and c = 44
Operator is >>= and c = 11
Operator is &= and c = 2
Operator is ^= and c = 0
Operator is |= and c = 2

Advantages:
1. Short hand expressions are easier to write.
2. The statement involving short hand operators are easier to read as they are more
concise.
3. The statement involving short hand operators are more efficient and easy to
understand.

Conditional operator (? : )
It is also called ternary operator because it takes three operands. It has the general form:
variable = expression1 ? expression2 : expression3;
If the expression1 is evaluated to true then it evaluates expression2 and its value is
assigned to variable, otherwise it evaluates expression3 and its value is assigned to variable.

It is an alternative to simple if..else statement

For example
#include<stdio.h>
int main()
{
int a=5,b=6,big;
big = a>b ? a : b;
printf("%d is big\n", big);
return 0;
}
Output
6 is big

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Special operators: Comma operator (,)

This operator allows the evaluation of multiple expressions, separated by the comma,
from left to right in the order and the evaluated value of the rightmost expression is accepted
as the final result. The general form of an expression using a comma operator is
expressionM= ( expression1, expression2, expressionN);
For example
#include<stdio.h>
int main() #include<stdio.h>
{ int main()
int k=5,i,j; {
i=k++, j=(k++,k++,++k); int k=5,i,j;
printf(“i=%d\t j=%d”, i,j); i=k++, j =k++, k++, ++k;
return 0; Printf(“i=%d \t j=%d”, i,j);
} return 0;

Output:i=5 j=6
Output: i=5 j=9

Sizeof() Operator
The operator sizeof is a unary operator used calculates the size of data types and
variables. The operator returns the size of the variable, data type in bytes. i.e. the sizeof
operator is used to determine the amount of memory space that the variable/data type will take.
The outcome is totally machine-dependent. For example:

#include<stdio.h>
int main()
{
printf("char occupies %d bytes\n",sizeof(char));
printf("int occupies %d bytes\n",sizeof(int));
printf("float occupies %d bytes\n",sizeof(float));
printf("double occupies %d bytes\n",sizeof(double));
printf("long double occupies %d bytes\n",sizeof(long double));
return 0;

}
Output
char occupies 1 bytes
int occupies 2 bytes
float occupies 4 bytes
double occupies 8 bytes
long double occupies 10 byte

1.14 Expressions :
In C programming, an expression is any legal combination of operators and operands
that evaluated to produce a value.Every expression consists of at least one operand and can
have one or more operators. Operands are either variables or values, whereas operators are
symbols that represent particular actions.
In the expression x + 5; x and 5 are operands, and + is an operator.
In C programming, there are mainly two types of expressions are available. They are as
follows:
1. Simple expression
2. Complex expression

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Simple expression: In which contains one operator and two operands or constants.
Example: x+y; 3+5; a*b; x-y etc.

Complex expression: In which contains two or more operators and operands or constants.
Example: x+y-z; a+b-c*d; 2+5-3*4; x=6-4+5*2 etc.

Operators provided mainly two types of properties. They are as follows:

1. Precedence and
2. Associativity

1. Operator Precedence
It defines the order in which operators in an expression are evaluated depends on their
relative precedence. Example: Let us see x=2+2*2
st
1 pass- 2+2*2
nd
2 pass- 2+4
rd
3 pass- 6 that is x=6.

2. Associativity
It defines the order in which operators with the same order of precedence are
evaluated. Let us see x=2/2*2
st
1 pass-- 2/2*2
nd
2 pass-- 1*2
rd
3 pass-- 2that is x=2
The below table lists C operators in order of precedence (highest to lowest) and their
associativity indicates in what order operators of equal precedence in an expression are
applied.

S.No Operators Associativity

( ) [ ] → . ++ (postfix) − −(postfix)
1 L to R
++ (prefix) -- (prefix) ! ~ sizeof(type) + (unary) − (unary) R to L
2
&(address) * (indirection)
*/%
3 L to R
+−
4 L to R
<<>>
5 L to R
<<= >>=
6 L to R
= = !=
7 L to R
8 & L to R
9 ^ L to R
10 | L to R
11 && L to R
12 || L to R
13 ?: R to L
= += −= *= /= %= >>= <<= &= ^= |=
14 R to L
15 , L to R
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 UNIT-I C Programming

An example ‘C’ program that illustrates the use of expressions

#include<stdio.h>
int main()
{
int a, b=4,c=8,d=2,e=4,f=2;
a=b+c/d+e*f; // expression1
printf(" The value of a is%d\n", a);
a=(b+c)/d+e*f; // expression2
printf("The value of a is%d\n", a);
a=b+c/((d+e)*f); //expression 3
printf("The value of a is%d\n", a);
return 0;
}

Output:
The value of a is 16
The value of a is 14
The value of a is 6

1.15 Type Conversion:

Type casting: Type casting is a way to convert a variable from one data type to another data
type. It can be of two types:
1. Implicit type casting
2. Explicit type casting

Implicit type casting

When the type conversion is performed automatically by the compiler without
programmer’s intervention, such type of conversion is known as implicit type conversion or
type promotion. In this, all the lower data types are converted to its next higher data type.

If the both operands are of the same type, promotion is not needed. If they are
not, promotion follows these rules:

 float operands are converted to double.

 char or short are converted to int.
 If anyone operand is double, the other operand is also converted to double, and that is
the type of result.
 If anyone operand is long, the other operand is also converted to long, and that is the
type of result.
 If anyone operand is unsigned, the other operand is also converted to unsigned, and
that is the type of result

M.Ramesh , Dept of CSE, IIIT-Nuzivid, RGUKT. Page 33

 UNIT-I C Programming

The smallest to the largest data types with respect to size are given as follows:

Fig. Conversion of types in a mixed expression

M.Ramesh , Dept of CSE, IIIT-Nuzivid, RGUKT. Page 34

 UNIT-I C Programming

A Sample ‘C’ program that illustares the use implicit type conversion
#include<stdio.h>
int main()
{
int sum, num=17;
char ch='A';
sum=num+ch;
printf("The value of sum=%d\n", sum);
return 0;
}
Output:
The value of sum= 82 i.e. sum=num+ch=>17+65 (ASCII value of ‘A’)

Explicit typecasting: Which is intentionally performed by the programmer for his requirement
in a C program? The explicit type conversion is also known as type casting.We can convert
the values from one type to another explicitly using the cast operator as follows:

Syntax
(data_type) expression;

Where, data_type is any valid C data type, and expression may be constant, variable or
expression.

The following rules have to be followed while converting the expression from one type to
another to avoid the loss of information:
1. All integer types to be converted to float.
2. All float types to be converted to double.
3. All character types to be converted to integer.
Let us look at some examples of type casting.

res = ( int ) 9.5;

9.5 is converted to 9 by truncation then assigned to res.

res = ( int ) 12.3 / ( int ) 4.2 ;
It evaluated as 12/4 and the value 3 is assigned to res.

res = ( double ) total / n;
total is converted to double and then division is done in float point mode.

res = ( int )(a + b);
The value of (a + b) is converted to integer and then assigned to res.

res = ( int )a + b;
a is converted to int and then added with b.

1.16 Mathematical Functions in C
The mathematical functions such as sin, cos, sqrt, log etc., are frequently used in
analysis of real-life problems. Most of the C compilers support these basic math functions. The
following Table lists some standard math functions

Function Meaning
Trigonometric
asin(x) Arc sin of x.
acos(x) Arc cosine of x
atan(x) Arc tangent of x
atan2(y,x) Arc tangent of y/x
sin(x) sine of x
M.Ramesh , Dept of CSE, IIIT-Nuzivid, RGUKT. Page 35
 UNIT-I C Programming

cos(x) cosine of x
tan(x) tangent of x
Hyperbolic
sinh(x) hyperbolic sine of x
cosh(x) hyperbolic cosine of x
tanh(x) hyperbolic tangent of x
Other functions
x
exp(x) e to the power of x (e )
ceil(x) x rounded up to the nearest integer.
floor(x) x rounded down to the nearest integer
fabs(x) absolute value |x|
log(x) Natural logarithm of x, x>0.
log10(x) Base 10 logarithm x, x>0.
fmod(x,y) Remainder of x/y
sqrt(x) square root of x, x>=0.
pow(x,y) x to the power y.

Note:
1 x and y should be declared as double.
2 In trigonometric and hyperbolic functions, x and y are radians.
3 All the functions return a double.
We should include the line:
#include<math.h>
in the beginning of the program

An example ‘C’ program that illustrates the use mathematical functions

#include <stdio.h>
#include <math.h>
int main()
{
printf("sin 90 = %.0f\n",sin(90));
printf("cos 0= %.0f\n",cos(0));
printf("sqrt(9) = %.0f\n",sqrt(9));
printf("floor(9.56) = %.2f\n",floor(9.56));
printf("ceil(9.56) = %.2f\n",ceil(9.56));
printf("abs(-9) = %.2f\n",fabs(-9));
printf("power(2,3) = %.0f\n",pow(2,3));
printf("Remainder of 9/3 = %.0f\n",fmod(9,3));
return 0;

Output
sin 90 = 1
cos 0= 1
sqrt(9) = 3
floor(9.56) = 9.00
ceil(9.56) = 10.00
abs(-9) = 9.00
power(2,3) = 8
Remainder of 9/3 = 0

M.Ramesh , Dept of CSE, IIIT-Nuzivid, RGUKT. Page 36