PHP for

Summary: in this tutorial, you will learn about PHP for statement to execute a block of code repeatedly.

Introduction to PHP for statement

The for statement allows you to execute a code block repeatedly. The syntax of the for statement is as follows:

<?php for (start; condition; increment) { statement; }
Code language: HTML, XML (xml)

How it works.

  • The start is evaluated once when the loop starts.
  • The condition is evaluated once in each iteration. If the condition is true, the statement in the body is executed. Otherwise, the loop ends.
  • The increment expression is evaluated once after each iteration.

PHP allows you to specify multiple expressions in the start, condition, and increment of the for statement.

In addition, you can leave the start, condition, and increment empty, indicating that PHP should do nothing for that phase.

The following flowchart illustrates how the for statement works:

When you leave all three parts empty, you should use a break statement to exit the loop at some point. Otherwise, you’ll have an infinite loop:

<?php for (; ;) { // do something // ... // exit the loop if (condition) { break; } }
Code language: HTML, XML (xml)

PHP for statement example

The following shows a simple example that adds numbers from 1 to 10:

<?php $total = 0; for ($i = 1; $i <= 10; $i++) { $total += $i; } echo $total;
Code language: HTML, XML (xml)

Output:

55

How it works.

  • First, initialize the $total to zero.
  • Second, start the loop by setting the variable $i to 1. This initialization will be evaluated once when the loop starts.
  • Third, the loop continues as long as $i is less than or equal to 10. The expression $i <= 10 is evaluated once after every iteration.
  • Fourth, the expression $i++ is evaluated after each iteration.
  • Finally, the loop runs exactly 10 iterations and stops once $i becomes 11.

Alternative syntax of the for statement

The for statement has the alternative syntax as follows:

for (start; condition; increment): statement; endfor;
Code language: PHP (php)

The following script uses the alternative syntax to calculate the sum of 10 numbers from 1 to 10:

<?php $total = 0; for ($i = 1; $i <= 10; $i++): $total += $i; endfor; echo $total;
Code language: HTML, XML (xml)

Output:

55

Summary

  • Use the PHP for statement to execute a code block in a specified number of times.
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