AWK - Control Flow

Like other programming languages, AWK provides conditional statements to control the flow of a program. This chapter explains AWK s control statements with suitable examples.

If statement

It simply tests the condition and performs certain actions depending upon the condition. Given below is the syntax of if statement −

Syntax

if (condition)
   action

We can also use a pair of curly braces as given below to execute multiple actions −

Syntax

if (condition) {
   action-1
   action-1
   .
   .
   action-n
}

For instance, the following example checks whether a number is even or not −

Example

[jerry]$ awk  BEGIN {num = 10; if (num % 2 == 0) printf "%d is even number.
", num } 

On executing the above code, you get the following result −

Output

10 is even number.

If Else Statement

In if-else syntax, we can provide a pst of actions to be performed when a condition becomes false.

The syntax of if-else statement is as follows −

Syntax

if (condition)
   action-1
else
   action-2

In the above syntax, action-1 is performed when the condition evaluates to true and action-2 is performed when the condition evaluates to false. For instance, the following example checks whether a number is even or not −

Example

[jerry]$ awk  BEGIN {
   num = 11; if (num % 2 == 0) printf "%d is even number.
", num; 
      else printf "%d is odd number.
", num 
} 

On executing this code, you get the following result −

Output

11 is odd number.

If-Else-If Ladder

We can easily create an if-else-if ladder by using multiple if-else statements. The following example demonstrates this −

Example

[jerry]$ awk  BEGIN {
   a = 30;
   
   if (a==10)
   print "a = 10";
   else if (a == 20)
   print "a = 20";
   else if (a == 30)
   print "a = 30";
} 

On executing this code, you get the following result −

Output

a = 30