Wednesday, 27 February 2013

Define looping. Discuss the types of looping structures used in C with examples.

Looping:

 The loop or iteration construct, directs a program perform a set of operation again and again until a specified condition is achieved.
This condition causes the termination of the loop.
C contains three statements for looping:

Ø    While Loop:  While loop construct contains the condition first. If the condition is satisfied the control executes the statement following the while loop exile, it ignores these statements.

Syntax:           while(condition)
                                    {           statement1
                                                Statement2
                                    }
Example: :     #include<stdio.h>
                                    #include<conio.h>
                        void main()
                                    {
                                                int x;
                                                X=1;
                                                while(x<10)
                                                {
                                                            printf(“x is %d /n”, x);
                                                            x++;
                                                }
                                    }
Ø    Do While Loop:  Do while loop ensure that the program execute at least once and checks whether the condition at the end of the do-while loop is true or false.
As long as the test condition is true the statement will be repeated. The control will come out from the loop only when the test condition is false.
Syntax:           do
                        {
                                    Statement1
                                                Statement1
                                    }while(condition)

Example: :     #include<stdio.h>
                                    #include<conio.h>
 void main()
                                    {
                                                int x;
                                                X=1;
                                                do
                                                {
                                                            printf(“x is %d /n”, x);
                                                            x++;
                                                } while(x<10)
                                    }




Ø    For loop construct is used to execute a set of statements for  a given number of times. Thus, it is a shorthand method for executing statement in a loop.
Syntax:           for(initial condition; test condition; increment or decrement)
                        {           Statement1
                                    Statement2
                        }

            Example:       #include<stdio.h>
                                    #include<conio.h>
void main()
                                    {
                                                int counter;
                                                for(counter=20; counter<=1; counter--)
                                                {
                                                            printf(“%d”, counter);
                                                }
                                    }

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