PHP翻转字符串实例

<?php
$str = "HelloWorld";
function reverseStr($str)
{
	if($str == '')
	    return null;
	if(strlen($str) == 1)
	{
		return $str;
	}else
	{
		$string = '';
		for($i = 1; $i <= strlen($str); $i++)
		{
			$string .= substr($str, -$i, 1);
		}
		return $string;
	}
}
echo reverseStr($str);
?>

output:

dlroWolleH