Reverse a string without using any functions
function reverse_string($s) {
$i = 0;
$rev = '';
while ( $s[$i] ) {
$i++;
}
$i--;
while ( $s[$i] ) {
$rev .= $s[$i];
$i--;
}
return $rev;
}
strrev
(PHP 4, PHP 5)
strrev — 文字列を逆順にする
説明
string strrev
( string
$string
)
string を逆順にして返します。
パラメータ
-
string -
逆順にしたい文字列。
返り値
逆順にした文字列を返します。
例
例1 strrev() で文字列を逆順にする
<?php
echo strrev("Hello world!"); // 出力は "!dlrow olleH" となります
?>
add a note
User Contributed Notes 4 notes
dthawkins+php at gmail dot com ¶
8 days ago
carmel.alex at gmail.com ¶
8 years ago
This function support utf-8 encoding
function utf8_strrev($str){
preg_match_all('/./us', $str, $ar);
return join('',array_reverse($ar[0]));
}
manfred at werkzeugH dot at ¶
5 years ago
here is my version for strings with utf8-characters represented as numerical entities (e.g. Ӓ)
function utf8_entities_strrev($str, $preserve_numbers = true)
{
//split string into string-portions (1 byte characters, numerical entitiesor numbers)
$parts=Array();
while ($str)
{
if ($preserve_numbers && preg_match('/^([0-9]+)(.*)$/',$str,$m))
{
// number-flow
$parts[]=$m[1];
$str=$m[2];
}
elseif (preg_match('/^(\&#[0-9]+;)(.*)$/',$str,$m))
{
// numerical entity
$parts[]=$m[1];
$str=$m[2];
}
else
{
$parts[]=substr($str,0,1);
$str=substr($str,1);
}
}
$str=implode(array_reverse($parts),"");
return $str;
}
MagicalTux at FF dot st ¶
8 years ago
I will make Screend at hf dot webex dot com's comment more clear and understandable.
strrev only works for singlebyte character-sets. Multibytes charactersets are not compatibles with strrev.
US-ASCII and ISO-8859-* are compatible with strrev, however BIG5, SJIS, UTF-8 aren't.
There's no mb_strrev function in PHP, so you can't strrev() a multibyte string. Try to convert it to something else with iconv() if it can be represented in a singlebyte character set.
