Basic Computation and Programming with C

In the previous chapter we have learnt to write simple C programs. The statements in the programs are executed sequentially, i.e., one after another as they appeared in the program. However, in practice, the problems are not so simple. We need to take decision whether a particular set of statements will execute or not; instead of one group of statements another group of statements may execute; even group of statements may execute repeatedly for known number of times or until certain condition are met. Thus the order of execution of statements has to be controlled. The statements which control the order of execution is known as Control statement. There are two type of control statement in C. These are:

• • Branching and

• • Looping

Branching statement decides what actions to take and loop statement decides how many times to execute a certain action. In this chapter, we discuss on several branching statements.

Branching is so called because the program chooses to follow one branch or another. This type of statements is also known as conditional statement as depending on the condition a certain set of statement(s) executes. C has mainly two branching statements – if statement and switch statement.

IF STATEMENT

The most important branching statement is if statement. It handles one way as well as two way decision. The if statement consists of two parts – a test expression and one or more statements or block of statements. The decision is taken based on the expression given in parenthesis with the if statement. If the expression is true then a particular statement or block of statements gets executed.