Ubuntu Unleashed 2013 Edition: Covering 12.10 and 13.04, Eighth Edition

Loops

PHP has four ways you can execute a block of code multiple times: while, for, foreach, and do...while. Of the four, only do...while sees little use; the others are popular, and you will certainly encounter them in other people’s scripts.

The most basic loop is the while loop, which executes a block of code for as long as a given condition is true. So, we can write an infinite loop—a block of code that continues forever—with this PHP:

<?php  $i = 10;  while ($i >= 10) {    $i += 1;    echo $i;  }?>

The loop block checks whether $i is greater or equal to 10 and, if that condition is true, adds 1 to $i and prints it. Then it goes back to the loop condition again. Because $i starts at 10 and we only ever add numbers to it, that loop continues ...