PHP - Using do...while loops

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Introduction

If the expression you're testing relies on setting a variable inside the loop, you need to run that loop at least once before testing the expression.

Demo

<?php

          $width = 1;/*  w ww .j  a va2  s . c  o m*/
          $length = 1;

          do {
            $width++;
            $length++;
            $area = $width * $length;
          } while ( $area  <  1000 );

          echo "The smallest square over 1000 sq ft in area is $width ft x $length ft.";
?>

Result

This script computes the width and height of the smallest square over 1000 square feet in area.

It initializes two variables, $width and $height.

Then creates a do...while loop to increment these variables and compute the area of the resulting square, which it stores in $area.

Because the loop is always run at least once, you can be sure that $area will have a value by the time it's checked at the end of the loop.

If the area is still less than 1000, the expression evaluates to true and the loop repeats.

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