字符串反转方法收集

$str = 'abcdef123';
echo strrev($str)

$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);

$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;