Sams Teach Yourself PHP in 24 Hours, Third Edition

Loops

So far we’ve looked at decisions a script can make about which code to execute. Scripts can also decide how many times to execute a block of code. Loop statements enable you to achieve repetitive tasks. Almost without exception, a loop continues to operate until either a condition is achieved or you explicitly choose to exit the loop.

The while Statement

The while statement looks similar in structure to a basic if statement:

while ( expression ) {
   // do something
}

As long as a while statement’s expression evaluates to true, the code block is executed repeatedly. Each execution of the code block in a loop is often called an iteration. Within the block, you usually change something that affects the while statement’s expression; otherwise, ...