Mastering the do-while Loop in PHP: A Complete Guide

The do-while loop is very similar to the while loop, but it does things in reverse order. The mechanism of the while loop is - while a condition is true, perform a certain action. The mechanism of the do-while loop is - perform a certain action while a condition is true.

Syntax:

<span class="pln">

</span><span class="kwd">do</span><span class="pun">{</span><span class="pln"> 
</span><span class="com">// execute this code;</span><span class="pln">
</span><span class="pun">}</span><span class="pln">

</span><span class="kwd">while</span><span class="pln"> </span><span class="pun">(</span><span class="pln">condition</span><span class="pun">);</span><span class="pln">

</span>

Example:

<span class="pln">

</span><span class="pun">&lt;?</span><span class="pln">php
$num </span><span class="pun">=</span><span class="pln"> </span><span class="lit">0</span><span class="pun">;</span><span class="pln">

</span><span class="kwd">do</span><span class="pun">{</span><span class="pln"> 
$num </span><span class="pun">=</span><span class="pln"> $num </span><span class="pun">+</span><span class="pln"> </span><span class="lit">5</span><span class="pun">;</span><span class="pln">
</span><span class="kwd">print</span><span class="pln"> $num </span><span class="pun">.</span><span class="pln"> </span><span class="str">"&lt;br /&gt;"</span><span class="pun">;</span><span class="pln">
</span><span class="pun">}</span><span class="pln">

</span><span class="kwd">while</span><span class="pln"> </span><span class="pun">(</span><span class="pln">$num </span><span class="pun">&lt;</span><span class="pln"> </span><span class="lit">25</span><span class="pun">);</span><span class="pln"> 
</span><span class="pun">?&gt;</span><span class="pln">

</span>

Output:

This will produce the following result

<span class="pln">

</span><span class="lit">5</span><span class="pln">
</span><span class="lit">10</span><span class="pln">
</span><span class="lit">15</span><span class="pln">
</span><span class="lit">20</span><span class="pln">
</span><span class="lit">25</span><span class="pln">

</span>

Flow chart

In the above code, a variable named num is initialized with the value of 5. The condition in the do-while loop is that while num is less than 25, 5 should be added to num. Once the value of num is greater than 25, the loop will stop executing.