EE-163(C&P) Lesson - I EED MHUH, FR
What is Programming?
Computer Programming is defined in wiki books as:
“Computer programming is the craft of writing useful, maintainable, and extensible source code which can
be interpreted or compiled by a computing system to perform a meaningful task.”
Computers are very helpful machines, but we need to program them before using. They can’t do anything
on their own. In order to get a task performed by a computer “you (or someone else) have to tell it exactly
- in excruciating detail - what to do. Such a description of "what to do" is called a program, and
programming is the activity of writing and testing such programs.”
In order to give instructions to the computer, we need to speak to them in a language they understand. Once
we are able to do that we can write instructions for computer. Just like any common language computer
languages also have some vocabulary and grammar. While using those languages it is essential to comply
with the language grammar and use correct vocabulary. Otherwise computer won’t understand us; it may
end up doing something wrong or may get angry at us and throw errors and warnings.
Details about evolution of computer languages can be seen in the book.
Ungraded Assignment:
i. Find differences between Programmers and Users
ii. Create a list of modern programming languages with their preferred targets
Integrated Development Environment (IDE)
In order to write programs using C++ language you need C++ compiler and a text editor. C++ compiler
converts the source code to computer understandable form. Text editor is required to type the source code.
Often there are computer programs that are combination of compiler and text editor. These programs are
referred as Integrated Development Environment (IDE) (they may be free of cost or paid). For this course
it is recommend to use an IDE called Code::Blocks. It is open source free of cost application targeting
Windows, Mac and Linux environment. Further details about code blocks can be obtained from
http://www.codeblocks.org/
Your First Code
les_01_code_01.cpp
1. #include<iostream>
2. using namespace std;
3.
4. int main()
5. {
6. cout<<"Hello world!";
7. return 0;
8. }
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EE-163(C&P) Lesson - I EED MHUH, FR
Let us traverse the code line by line
Line
Description
No
Pre Processor Directive
to make available facilities from file iostream.h into this program
1 iostream is used when it is required to show some output on monitor, or take input from the
keyboard.
This directive will essentially be present in all the codes we will develop in this course
namespace is an advanced idea, for now just consider it as part of library
2
This line will also be present in all codes
3 A blank space; it has no effect on processing. Used just to make the code look tidy
this is the main function definition (main is a name and reserved keyword for C++)
Every C++ program must have a function called main to tell it where to start. A function is a
named sequence of instructions for computer to execute in order in which they are written. A
function has four parts:
i. A return type (here it is int)
4
ii. Name (main here)
iii. Parameter list (empty here)
iv. Function body, enclosed in a set of curly braces { }, which lists the actions called
statements that the function is to perform.
5 Opening brace { of the main function.
cout (see out) it’s the standard output stream (print to console).
followed by the symbol << this is put to operator (stream insertion operator) which indicates
what ever follows this will be put to standard output (monitor).
Then we have “Hello world!” this is string, a fundamental data type in C++ and it is
6
recogonized with “ ” .
then we have a semicolon ; this is the end of the statement.
Every C++ statement should terminate with a semicolon, this is how compiler recognize that
a statement is completed.
return 0; this is the return value of main (for time being just consider this is the standard
7 procedure until we discuss functions).
A zero (0) returned by main() indicates the program terminated successfully.
8 Closing brace } of the main function.
Understanding endl
les_01_code_02.cpp
1. #include<iostream>
2. using namespace std;
3.
4. int main()
5. {
6. cout<<"Hello"<<endl<<"world!";
7. return 0;
8. }
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EE-163(C&P) Lesson - I EED MHUH, FR
Exercise
Predict output of the following statements
Statement Output
cout << "Hello” world!" << endl;
cout << "Hello”; world!" << endl;
cout << "Hello" ;
cout <<" world!" << endl;
Ungraded Task
Write a program that prints the following
Hello Your Name!
Welcome to C++ Programming
Bonus Material
IEEE Spectrum Top Ten Programming languages
https://spectrum.ieee.org/computing/software/the-2017-top-programming-languages
Understanding Data Types
Data types, defines the proper use of an identifier and expression. An expression is a sequence of operators
and their operands that specifies a computation. Various data items with symbolic names in C++ is called
as identifiers. Following data items are identifier in C++
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• Names of functions
• Names of arrays
• Names of variables
• Names of classes
Data types are important to understand because certain operations can only be performed on certain data
types. Following chart shows the broad categories of data types available in C++
Data Types
Numeric String Character Boolean
(bool) True (1)
Integer (int) e.g. (string) e.g (char) Single
or False (0)
32, 107, 13390 "Hello World" Letter e.g. 'a', 'f'
Value
Float (double)
e.g. 3.1413, 53.7
Numeric Data Types
Whole Numbers or Integers
• int can store number hold upto 4 bytes can store number from -2,000,000,000 to +2,000,000,000
(approximately)
• unsigned int can hold up to 4 bytes (only positive numbers) but that doubles the positive range,
ranges between 0 – 4,000,000,000
Data Types for floating point numbers
• double Size is 8 bytes +-1.7 e + - 308;
• float 4 bytes
Data Types for Alpha Numeric
string
a string is zero or more characters surrounded by double quotes. E.g. “Hello World!”, “100”,
char
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Only a single character can be stored in a variable of type char, char values are stored as an integer, based
on ASCII value of character e.g. ‘a’
char was important data type when systems had less memory, now a days memory in the systems is ample
so char is not much useful now.
Boolean Data
bool
bool is another data type, it holds true (1) or false (0) values.
Primitive Built-in Types
C++ offer the programmer a rich assortment of built-in as well as user defined data types. Following table
lists down seven basic C++ data types:
Type Keyword
Boolean bool
Character char
Integer int
Floating point float
Double floating point double
Valueless void
Wide character wchar_t
Several of the basic types can be modified using one or more of these type modifiers:
• signed
• unsigned
• short
• long
The following table shows the variable type, how much memory it takes to store the value in memory, and
what is maximum and minimum value which can be stored in such type of variables.
Type Typical Bit Width Typical Range
char 1byte -127 to 127 or 0 to 255
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unsigned char 1byte 0 to 255
signed char 1byte -127 to 127
int 4bytes -2147483648 to 2147483647
unsigned int 4bytes 0 to 4294967295
signed int 4bytes -2147483648 to 2147483647
short int 2bytes -32768 to 32767
unsigned short int Range 0 to 65,535
signed short int Range -32768 to 32767
long int 4bytes -2,147,483,647 to 2,147,483,647
signed long int 4bytes same as long int
unsigned long int 4bytes 0 to 4,294,967,295
float 4bytes +/- 3.4e +/- 38 (~7 digits)
double 8bytes +/- 1.7e +/- 308 (~15 digits)
long double 8bytes +/- 1.7e +/- 308 (~15 digits)
wchar_t 2 or 4 bytes 1 wide character
Variables
Variables are named objects with a specific type. (Object is a region of memory with a type.) Variables
can be used to store data of a certain type which can later be used in the program. A variable must be
declared using a legal keyword (listed in table above) and a legal name. Following are the rules to assign
variable names:
• Variable name must start with a letter or _ (underscore)
• May contains letter, numbers and the underscore character
• Examples: salary, firstName, name3, first_name, _newVal
• Illegal : 3name, first name, new, class, struct, while, for, my@val
• Uppercase and lower case are distinct
Programs to Understand Variables and Data Types
les_01_code_03.cpp
1. #include<iostream>
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2.
3. using namespace std;
4.
5. int main()
6. {
7. int num1;
8. num1 = 2;
9.
10. char sym;
11. sym = '@';
12.
13. string name;
14. name = "Leo Tolstoy";
15.
16. cout<<"You inserted "<<num1<<" as num1"<<endl;
17. cout<<"You inserted "<<sym<<" as sym"<<endl;
18. cout<<"You inserted "<<name<<" as name"<<endl;
19.
20. return 0;
21. }
Output
les_01_code_04.cpp
1. #include<iostream>
2.
3. using namespace std;
4.
5. int main()
6. {
7. int num2 = 2.5; // Initialization statement
8. cout<<num2;
9.
10. return 0;
11. }
Output
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Declaring Multiple Variables of same type
les_01_code_05.cpp
1. #include<iostream>
2.
3. using namespace std;
4. int main ()
5. {
6. int num1, num2, num3;
7. int num4, num5 = 10, num6;
8. int num7 = 20, num8 = 30, num9 = 40;
9.
10. return 0;
11. }
Common Mistakes
les_01_code_06.cpp
1. #include<iostream>
2.
3. using namespace std;
4.
5. int main()
6. {
7. int num1 = 7;
8. cout<<Num1;
9.
10. cout<<num2;
11. int num2;
12.
13. strings name;
14.
15. return 0;
16. }
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EE-163(C&P) Lesson - I EED MHUH, FR
Interactive Computing
Often it is required in a program to take input from the user in run time. This idea of interacting with the
user is called interactive computing. This can be done in C++ thorough standard input stream object cin
(of namespace std) and the stream extraction operator >> (also called get from operator). The following
code will help you to understand the idea.
les_01_code_07.cpp
1. #include<iostream>
2.
3. using namespace std;
4.
5. int main()
6. {
7. int num1;
8. cout<<"Please enter the value of num1 : ";
9. cin>>num1;
10. cout<<"You Entered : "<<num1;
11.
12. return 0;
13. }
Output
Taking Multiple Inputs
les_01_code_08.cpp
1. #include<iostream>
2.
3. using namespace std;
4.
5. int main()
6. {
7. int num1, num2, num3;
8. cout<<"Please enter the value of num1, num2, num3 : ";
9. cin>>num1>>num2>>num3;
10. cout<<"You Entered : num1 "<<num1<<endl;
11. cout<<"You Entered : num2 "<<num2<<endl;
12. cout<<"You Entered : num3 "<<num3<<endl;
13. return 0;
14. }
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Possible Outputs
i. Entering values separated by space (whitespace is delimiter for cin)
Notice the space
ii. Entering Values separated by Return Key
Notice the Enter Key
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EE-163(C&P) Lesson - I EED MHUH, FR
Careful with Strings
les_01_code_09.cpp
1. #include<iostream>
2.
3. using namespace std;
4.
5. int main()
6. {
7. string name;
8. cout<<"Please enter the name : ";
9. cin>>name;
10. cout<<"Name you entered is : "<<name;
11. return 0;
12. }
Output
Note that whitespace is delimiter for the cin so everything you typed after Leo is lost
Remedy
Use getline() function to input strings
les_01_code_10.cpp
1. #include<iostream>
2.
3. using namespace std;
4.
5. int main()
6. {
7. string name;
8. cout<<"Please enter the name : ";
9. getline(cin,name);
10. cout<<"Name you entered is : "<<name;
11.
12. return 0;
13. }
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Output
Run 1
Run 2
Beware that getline can only be used to input strings
Exercise
Write a program that stores speed of light, Planck’s constant, charge on electron,
Avagadro’s number, your age, your full name, your department, your cgpa in
appropriate variables and print them on console.
Re implement the same program, this time making it interactive by involving user
input.
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