DECISION MAKING AND LOOPING

DECISION MAKING AND LOOPING

INTRODUCTION

It is possible to execute a segment of a program repeatedly by introducing a counter and later testing it using the if statement and goto statement. It forms a loop. In looping, a sequence of statements are executed  until some conditions for termination of the loop are satisfied. A program loop consists of two segments, one known as the body of the loop and the other known as the control statement. The control statement tests certain conditions and then directs the repeated execution of the statements contained  in the body of the loop. Depending on the position of the control statement in the loop, a control structure may be classified either as the entry-controlled loop or as theexit-controlled loop.

In entry-control loop, the control conditions are tested before the start of the loop execution. If the conditions are not satisfied, then the body of the loop will not be executed. In the case of an exit-controlled loop,the test is performed at the end of the body of the loop and therefore the body is executed unconditionally for the first time.

A looping process, in general, would include the following four steps:

1. Setting and initialization of a counter.
2. Execution of the statements in the loop.
3. Test for a specified condition for exection of the loop.
4. Incrementing the counter.

The C language provides for three loop constructs for performing loop operations. They are:

1.The while statement
2.The do - while statement
3. The for statement

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