Computer Programming Eng.

106
Wednesday September 22, 2010
Objective:Introduction to C++
Arithmetic Operators
Input and Output, Variables and Comments
Integer Division and Modulus
Internal Coding of Integer Numbers
Definition 1: A computer program is a step-by-step
descriptions of the solution to a problem. It is written in
C++ code (i.e., C++ statements).

Definition 2: C++ is a programming language containing

a set of instructions called statements. These statements
are understandable by the computer machine.

Definition 3: The computer uses its memory called RAM

(Random Access Memory), to store the program.

Definition 4: The computer uses its brain called

processor (CPU) to perform the C++ statements.

Definition 5: The C++ program has a well defined

structure as follows:
1 #include <iostream.h>
2 void main()
The C++ Program
3 { Structure
4 Statements;
5 }
This C++ program is written by you using the keyboard.
It will be stored into a text file and has a given name like
program1.cpp or ProgHello.cpp

Prof. Jihad Mohamd ALJA'AM 1

 Example

#inculde <iostream.h>
This is a C++ program.
void main()
{
It has one statement:
cout << “Hello, World”;
cout << “Hello, World”;
}

Storage in RAM
Output Primary Storage

Computer SCREEN RAM contains Program

Random Access Memory

Hello, World RUN #inculde <iostream.h>

void main()
{
cout << “Hello, World”;
}

Store Storage in Hard Disk

Secondary Storage

The program is stored Hard Disk: C

into the hard disk C.
#inculde <iostream.h>
You should give it a void main()
name like: {
cout << “Hello, World”;
}
ProgHello.cpp

Rules of Thumbs

1. Keyboard (Write Program, or Input Program).

2. Store Program in Computer Memory (RAM).
3. Run Program (PROCESSOR).
4. Output Results (SCREEN).
5. Storage of Program (HARD DISK C).

Prof. Jihad Mohamd ALJA'AM 2

 Computer Components

Keyboard: Input Program

Temporary Hold Program

Storage but needs
Power

RAM: Primary Storage

Processor: Run Program

Screen: Output Results

Hold Program
Permanent With or Without
Storage Power
Hard Disks: Secondary Storage

The program is stored into the hard disk C through a text

file having a name like: ProgHello.cpp

Prof. Jihad Mohamd ALJA'AM 3

The Text File stored into theHard Disk C: ProgHello.cpp

#include <iostream.h>
void main()
{
cout << “Hello, World”;
}

This is a text file that will be stored into the hard disk of
your computer.

ProgHello.cpp Hard Disk: C

You can open the program, update it (Add and

Remove things) and re-save it with the same
name.

You should compile the program in order to

run it. Compile means error-checking.

A compiled program is error-free and can then

be run and produce the results.

Prof. Jihad Mohamd ALJA'AM 4

 Some Simple C++ Program

#include <iostream.h>
void main()
{
cout << “************\n”;
cout << “Hello, World\n”;
cout << “************”;
}

************
Hello, World
************

#include <iostream.h>
void main()
{
cout << “ *\n”;
cout << “ ***\n”;
cout << “ *****”;
}

*
Screen
*** Output
*****

Prof. Jihad Mohamd ALJA'AM 5

 #include <iostream.h>
void main()
{
cout << “********\n”;
cout << “********\n”;
cout << “********”;
}

*******
Screen
******* Output
*******

#include <iostream.h>
void main()
{
cout << “5 + 8 = ”;
cout << 5+8;
}

5 + 8 = 13

Prof. Jihad Mohamd ALJA'AM 6

Definition 6: The C++ uses a specific software called
compiler to check the correctness of your program and
convert it to assembly and (0,1)-Language.

Your Program
Checking (Compiler)
(0,1)-Language

Program1.cpp
Program1.obj
Program1.exe

The compiler issues the list of errors encountered in your

program. They are called syntax error.

#include <iostream.h>
void main() COMPILE
{ Syntax Error
cot << “ *\n”; “cot” not
cout << “ ***\n”; declared

cout << “ *****”;

}

The compiler will automatically detect the syntax error

.obj
Program

No Syntax error
Compiler issues

.exe
Program

SCREEN Output Results Run .exe

Prof. Jihad Mohamd ALJA'AM 7

Definition 7: The C++ package contains an IDE
(Integrated Environment) which allows you to write your
program, give it a name, save it into your hard disk,
compile it and run it to see the result.

Definition 8: The computer uses its RAM (internal

memory) to store the program (called the C++ code), the
data and the result.
Random Access Memory
PROGRAM
DATA
RESULT
RAM

Processor:
CPU

Definition 8: The RAM needs power to work and store

the Program. It is called Primary Storage Area.

Definition 9: The computer sends the program to the

hard disk to save it permanently. The hard disk is called
Secondary Storage Area (Permanent Storage).

Prof. Jihad Mohamd ALJA'AM 8

 RAM (Random Access Memory) STRUCTURE

Addresses Location

1 data
2 data
3 data
4 data
5 data
6 data
.
.
.

• Addresses are expressed in Hexadecimal

(i.e., numbers in base 16).

• Every memory location can contain one

data in binary (0,1).

Prof. Jihad Mohamd ALJA'AM 9

 C++ Programming Language

This powerful programming language is formed of a

subset of the English language. A set of English words
called keywords or reserved words.

Here are some of these keywords:

cin, cout, if, for, while, main, int,

float, double, unsigned, char, switch,
case, void, return, etc.

Every key word has a specific meaning. Whenever we

mistakenly write a keyword, a syntax error is generated.

Example: if we write cot instead of cout, the C++

complier generated a syntax error for the word cot.

The C++ language recognizes the numbers like integer

and real numbers positive and negative.

123, 34.5, -324, -45.6, 342.521, etc

It also recognizes the arithmetic operators:

+, -, /, *, %, etc

In addition, there is a library allowing C++ to recognize

the mathematical functions like:

sin, cos, tan, sqrt, etc

Prof. Jihad Mohamd ALJA'AM 10

 This is a list of reserved keywords in C++
Keyword Description
and alternative to && operator
and_eq alternative to &= operator
asm insert an assembly instruction
(C++0x) automatically detect variable type from initializer
auto
expression (meaningless declare a local variable in pre-C++0x)
bitand alternative to bitwise & operator
bitor alternative to | operator
bool name of builtin boolean type
break break out of a loop
case in switch statement, defines a value label
catch handles exceptions from throw
char name of builtin character type (also 8-bit integer type)
class declare a class
compl alternative to ~ operator
modifier for a variable, a pointer to, or a reference to, which states
const
that the variable cannot be modified
const_cast cast that only allows to strip 'const' or 'volatile' modifiers
continue bypass iterations of a loop
default handler in a case statement (in C++0x also force default
default
implementation of a method)
make dynamic memory available (in C++0x also remove a method
delete
that would be provided by default otherwise)
do begin of a 'do-while' looping construct
double name of a builtin double precision floating-point type
cast a pointer/reference from base (polymorphic) class to derived
dynamic_cast
class, with runtime error reporting, if cast is not correct
else alternate case for an if statement
enum declare an enumeration type
make a class's one-argument constructor not allowed to be used for
explicit
implicit conversions
states that the following template declaration will be defined in
export
another compilation unit
declares an external linkage for a variable (if not initialized, provides
only forwarding declaration for a variable to be declared either later
extern
or in another compilation unit) or (extern “C”) declares C linkage for
a function
false a constant representing the boolean false value
float name of a single precision floating-point type

Prof. Jihad Mohamd ALJA'AM 11

for looping construct
friend grant non-member function access to private data
goto jump to a label (within the same function)
if execute code based on the result of a test
declare that a function is to be expanded in place when called (or to
inline
undergo vague linkage, if expanding is not possible)
int name of a builtin default integer type
long name of a builtin long integer variable
mutable wipe constness from a class's field, when whole object is const
namespace partition the global namespace by defining a scope
new create an object, allocating memory from dynamic pool
not alternative to ! operator
not_eq alternative to != operator
operator create overloaded operator functions
or alternative to || operator
or_eq alternative to |= operator
private declare private members of a class
protected declare protected members of a class
public declare public members of a class
request that a variable be implemented by machine's register rather
register
than on function's stack
cast between any pointers or any integer with no change, which does
reinterpret_cast
not strip const or volatile modifiers
return return from a function
short declare a short integer variable
signed modify variable type declarations
sizeof return the size of a variable or type
static create permanent storage for a variable
cast that can be done implicitly in reverse, with changing the pointer
static_cast
for derived class, if required
struct define a new structure
switch execute code based on different possible values for a variable
template create generic functions or classes
this a pointer to the current object inside a class's method
throw throws an exception
true a constant representing the boolean true value
try execute code that can throw an exception
typedef create a new type name from an existing type
typeid describes an object
declare that the identifier next to this word must be always
typename interpreted as type (and not a variable or function), also declares type
parameter for template

Prof. Jihad Mohamd ALJA'AM 12

 a structure that assigns multiple variables to the same memory
union
location
unsigned modifier for integer types that makes them only positive range
using import complete or partial namespaces into the current scope
virtual create a function that can be overridden by a derived class
void name of a builtin void type or declare no return value in function
volatile warn the compiler about variables that can be modified unexpectedly
wchar_t name of a builtin wide-character type
while begin of 'while' or end of 'do-while' looping constructs
xor alternative to ^ operator
xor_eq alternative to ^= operator

Prof. Jihad Mohamd ALJA'AM 13

 Arithmetic Operations in C++
Operator Name
+ Addition
– Subtraction
/ Division
* Multiplication

Example

#include <iostream.h>
void main()
{
cout << “6*3 = ” << 6*3 << endl;
cout << “6-3 = ” << 6-3 << endl;
cout << “6/3 = ” << 6/3 << endl;
cout << “6+3 = ” << 6+3 << endl;
}

6*3 = 18
6-3 = 3
6/3 = 2
6+3 = 9

Prof. Jihad Mohamd ALJA'AM 14

 Reading of Data
Statement cin

Read data from the standard input device (Keyboard).

Syntax

cin >> Variable ;

Read data from the standard input device (Keyboard) and

store it at Variable (a location in RAM).

Example

cin >> X ;

Read data from the Keyboard and store it at X (into

RAM, the computer memory);

X can be: integer, float, char, …

Exercise-1: Read an integer from the

keyboard and store it at X.

Integers: 45, -102, 342, 25, -12

Prof. Jihad Mohamd ALJA'AM 15

Solution
COMMENTS
// Program done by Fatma
// Date: Monday Sep 20, 2010
1 #include <iostream.h>
2 void main()
3 {
4 int X; // X is a number
5 cout << "Enter The Value X = ";
6 cin >> X;
7 cout << "X = " << X;
8 }
1: input-output: To allow read and
write (use of cin and cout).

2: the main program: To allow the

proper start of the program.

3: {: To begin the program.

4: Declare a variable X of type

integer. X can receive integers.

5: Display a message. We prompt the

user to enter the value of X.

6: cin >> X: Read an integer from the

keyboard and store it at X. The user
should type in the integer number and
press the button "Enter".

7: Display two messages X and its

value.

8: }: To close the program.

Prof. Jihad Mohamd ALJA'AM 16

#include <iostream.h>
void main()
{
int X; // X is a number
cout << "Enter The Value of X = ";
cin >> X;
cout << "X = " << X;
}

Enter The Value X = 34

X = 34

Exercise-1: Run all the previous

programs on your computer machine and
see the results. Bring a printed copy
next lecture.

Exercise-2: Write a C++ program that

asks the user to enter his current age
and display his age of next year.

Exercise-3: Find ERRORS and CORRECT.

#include <iostraam.h>
void main ()
{ ;
cout << “8%3 = ” << “8%3” << endl;
cont; << 16-3 = ” << 16-“3” <<\n;;
cout << “9/3 = ” << 9/3 << end;
}
Prof. Jihad Mohamd ALJA'AM 17
Prof. Jihad Mohamd ALJA'AM 18