How to reverse string in PHP

How to reverse strings in PHP: 1. Reverse the string through the strrev function that comes with PHP; 2. Split the string into an array, and then traverse and concatenate it to reverse the string; 3. , just use recursion to reverse the string.

The operating environment of this article: windows7 system, PHP7.1 version, DELL G3 computer

Three ways of php reversing strings Method

Method 1: PHP has its own function strrev that can be easily implemented:

Reverse the string "Hello World!":

<?php
echo strrev("Hello World!");
?>

Method 2: Split the string into an array, and then traverse and splice it, as follows:

function revstr($str)
{
if (strlen($str) <= 1) return $str;
 
$newstr  = &#39;&#39;;
$str2arr = str_split($str,1);
foreach ($str2arr as $word) {
$newstr = $word.$newstr;
}
 
return $newstr;
}

Method 3: This method is the easiest to think of. In addition, there is another method, which is to use recursion. Code As follows:

function revstr($str)
{
if (strlen($str) <= 1) return $str;
 
$newstr = &#39;&#39;;
$newstr .= substr($str,-1).revstr(substr($str,0,strlen($str)-1));
 
return $newstr;
}

ps: This method should be the answer the interviewer wants to see.

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