1.单字节字符串反转
php提供了现成的用于字符串反转的函数strrev()
$str = ‘abcdef123‘; echo strrev($str)
2.对于包含中文的多字节字符串需要用到mb_substr()
$str = ‘字符串反转‘; function rev($str, $encoding = ‘utf-8‘){ $len = mb_strlen($str); $result = ‘‘; for ($i = $len-1; $i>=0; $i--){ $result.= mb_substr($str,$i,1,$encoding); } return $result; } echo rev($str);
3.算法实现 首位交换
$str = ‘abcdefg123‘; $len = strlen($str); $times = $len/2; for($i = 0;$i <= $times; $i++ ){ $tmp = $str[$i]; $str[$i] = $str[$len-$i-1]; $str[$len-$i-1] = $tmp; } echo $str;