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(PHP 4, PHP 5)
strrev — Kehrt einen String um
Gibt string in umgekehrter Reihenfolge zurück.
Die umzukehrende Zeichenkette.
Gibt die umgekehrte Zeichenfolge zurück.
Beispiel #1 Umkehren eines Strings mit strrev()
<?php
echo strrev("Hallo Welt!"); // Ausgabe: "!tleW ollaH"
?>
manfred at werkzeugH dot at, your version works, but do you think it has an advantage over mine? Just wondering if I should update my scripts.
carmel.alex at gmail.com, your version fails with utf8_strrev($string, true). It's something about spaces.
For example, you turn
This software was protected by 2000 patents since 2001
into
2001 ecnis stnetap2000 yb detcetorp saw erawtfos sihT
(note the "stnetap2000").
here is my version for strings with utf8-characters represented as numerical entities (e.g. Ӓ)
function utf8_entities_strrev($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;
}
MOD10, Modulus10 or also called LUHN10 will generate a valid check digit.
<?php
$inv = "34586";
echo $inv . checkdigit($inv);
// Outputs 345868
function checkdigit($num) {
$sum = 0;
$pos = 0;
$rev = strrev($num);
$len = strlen($num);
if ($len % 2 == 0) $len += 1;
while ($pos < $len) {
$odd = $rev[$pos] * 2;
if ($odd > 9) {
$odd -= 9;
}
$sum += $odd;
if ($pos != ($len - 2)) {
$sum += $rev[$pos +1];
}
$pos += 2;
}
return ((floor($sum/10) + 1) * 10 - $sum) % 10;
}
?>
to lwc at mytrashmail dot com, take it easy.
function utf8_strrev($str, $reverse_numbers = true){
$pattern = $reverse_numbers ? '/./us' : '/(\d+)?./us';
preg_match_all($pattern, $str, $ar);
return join('',array_reverse($ar[0]));
}
just as well for UTF-8 usages = I meant also for NONE UTF-8 usages (to keep the numbers unchanged)
/*
Here's a function that adds to carmel.alex's utf-8 encoding support the ability NOT to reverse numbers (for example when you output a phrase as a parameter for a SWF file that can't handle RTL languages itself, but obviously any numbers should remain the same as in the original phrase).
Note that it can be used just as well for UTF-8 usages if you want the numbers to remain intact:
*/
function utf8_strrev($str, $reverse_numbers) {
preg_match_all('/./us', $str, $ar);
if ($reverse_numbers)
return join('',array_reverse($ar[0]));
else {
$temp = array();
foreach ($ar[0] as $value) {
if (is_numeric($value) && !empty($temp[0]) && is_numeric($temp[0])) {
foreach ($temp as $key => $value2) {
if (is_numeric($value2))
$pos = ($key + 1);
else
break;
}
$temp2 = array_splice($temp, $pos);
$temp = array_merge($temp, array($value), $temp2);
} else
array_unshift($temp, $value);
}
return implode('', $temp);
}
}
// "It says this site is copyrighted just from 2001" (in Hebrew)
$str = "כתוב שהאתר הזה מוגן בזכויות יוצרים רק מאז 2001";
// Reverse everything
$str_blind_reverse = utf8_strrev($str, true);
// Reverse everything but don't change the year 2001 to 1002...
$str_logical_reverse = utf8_strrev($str, false);
This function support utf-8 encoding
function utf8_strrev($str){
preg_match_all('/./us', $str, $ar);
return join('',array_reverse($ar[0]));
}
Just a correction to the previous commenter. In ISO 8859-15, the Euro is 0xA4 (164 decimal). It is a 1 byte character.
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-8859-1 are compatible with strrev, however BIG5, SJIS, UTF-8 aren't.
Despite what you can think, ISO-8859-15 *is* multibyte (the euro symbol - - is coded on two bytes).
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.
strrev() can be very useful in cases where it makes more sense to do something from the end of a string rather than the beginning (well duh!) such as apply certain regular expressions. Here's a small function to add commas to numbers that works in such a way.
<?php
echo commafy("1500000.1254"); // prints 1,500,000.1254
function commafy($_) {
return strrev( (string)preg_replace( '/(\d{3})(?=\d)(?!\d*\.)/', '$1,' , strrev( $_ ) ) );
}
?>
I originally wrote it in Perl, does it show? ;=)
this function can only reverse the 1-byte words,like english,it seems,using
<?php
$str=strrev("");
echo $str;
?>
do not get a right result.
but,you can change 2-bytes characters into a ASCLL,the converse it.
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