Perl for Loop

Perl Loops

The Perl for loop is used to execute a sequence of statements multiple times, simplifying the code that manages loop variables.

Syntax

The syntax is as follows:

for ( init; condition; increment ){
   statement(s);
}

Here is the control flow analysis of the for loop:

• init is executed first and only once. This step allows you to declare and initialize any loop control variables. You can also leave this step empty as long as there is a semicolon.

• Next, the condition is evaluated. If it is true, the loop body is executed. If it is false, the loop body is not executed and control flow jumps to the statement following the for loop.

• After executing the loop body, control flow jumps back to the increment statement. This statement allows you to update the loop control variables. This statement can be left empty as long as there is a semicolon after the condition.

• The condition is evaluated again. If it is true, the loop is executed, and this process repeats (loop body, then increment, then re-evaluate the condition). When the condition becomes false, the for loop terminates.

Here, statement(s) can be a single statement or a block of several statements.

The condition can be any expression, and the loop executes when the condition is true and exits when the condition is false.

Flowchart

Example

#!/usr/bin/perl

# Execute the for loop
for( $a = 0; $a < 10; $a = $a + 1 ){
    print "a 的值为: $a\n";
}

Executing the above program will output:

a 的值为: 0
a 的值为: 1
a 的值为: 2
a 的值为: 3
a 的值为: 4
a 的值为: 5
a 的值为: 6
a 的值为: 7
a 的值为: 8
a 的值为: 9

Perl Loops