str_replace
Here's my implementation of a str_rot that takes a custom offset. It's faster than the others here because it allocates the output string in one go instead of tacking on characters one at a time. It can handle positive or negative offsets of any size, and it fixes everything up to ensure only upper and lower case letters are translated and that they wrap around correctly within the alphabet.
<?php
function str_rot($s, $n = 13) {
$n = (int)$n % 26;
if (!$n) return $s;
for ($i = 0, $l = strlen($s); $i < $l; $i++) {
$c = ord($s[$i]);
if ($c >= 97 && $c <= 122) {
$s[$i] = chr(($c - 71 + $n) % 26 + 97);
} else if ($c >= 65 && $c <= 90) {
$s[$i] = chr(($c - 39 + $n) % 26 + 65);
}
}
return $s;
}
?>
str_rot13
(PHP 4 >= 4.2.0, PHP 5)
str_rot13 — 문자열에 rot13 변환을 수행
설명
string str_rot13
( string $str
)
str 인수에 ROT13 인코딩을 수행하고, 결과 문자열을 반환합니다.
ROT13 인코딩은 간단히 모든 알파벳을 13만큼 쉬프트하고, 알파벳이 아닌 문자는 건들이지 않습니다. 인코딩과 디코딩은 같은 함수로 이루어지며, 인코드한 문자열을 인수로 전달하면 원 문자열을 반환합니다.
인수
- str
-
입력 문자열.
반환값
주어진 문자열의 ROT13 버전을 반환합니다.
예제
Example #1 str_rot13() 예제
<?php
echo str_rot13('PHP 4.3.0'); // CUC 4.3.0
?>
변경점
| 버전 | 설명 |
|---|---|
| 4.3.0 | 이 함수의 동작을 고쳤습니다. 고치기 전에는, 참조로 전달한 것처럼 str 도 변경되었습니다. |
add a note
User Contributed Notesstr_rot13
shaunspiller at spammenotgmail dot com
27-Sep-2009 12:54
27-Sep-2009 12:54
peter at NOSPAM jamit dot com
07-Sep-2009 11:31
07-Sep-2009 11:31
This ROT13 variant is different from my earlier version in that it retains 'ethnicity'. For example, a Chinese text when encrypted will remain Chinese, and the string will not be making sense (the real meaning will be encrypted). Just look at the code and you will understand.
<?php
function unichar2ords($char, $encoding = 'UTF-8') {
$char = mb_convert_encoding($char, 'UCS-4', $encoding);
$val = unpack('N', $char);
return $val[1];
}
function ords2unichar($ords, $encoding = 'UTF-8'){
$char = pack('N', $ords);
return mb_convert_encoding($char, $encoding, 'UCS-4');
}
function mbStringToArray ($string, $encoding = 'UTF-8') {
if (empty($string)) return false;
for ($strlen = mb_strlen($string, $encoding); $strlen > 0; ) {
$array[] = mb_substr($string, 0, 1, $encoding);
$string = mb_substr($string, 1, $strlen, $encoding);
$strlen = $strlen - 1;
}
return $array;
}
function unicodeRotN($str, $offset, $encoding = 'UTF-8') {
$val = '';
$array = mbStringToArray ($str, $encoding = 'UTF-8');
$len = count($array);
for ($i = 0; $i < $len; $i++) {
$val .= ords2unichar(unichar2ords($array[$i], $encoding) + $offset, $encoding);
}
return $val;
}
// example
$original = '中國是我的家'; // means "China is my home"
$encrypted = unicodeRotN($string, 13); // 为團昼戞皑寃 means "Ñ Ai injustice for the Mission Day" (Google translation)
$decrypted = unicodeRotN($encrypted, -13); // 中國是我的家
?>
peter at NOSPAM jamit dot com
07-Sep-2009 05:11
07-Sep-2009 05:11
Here is my ROT13 function that works for all possible characters and not just ASCII. It can be used on Chinese, Japanese, ....
<?php
function rot13encrypt ($str) {
return str_rot13(base64_encode($str));
}
function rot13decrypt ($str) {
return base64_decode(str_rot13($str));
}
// example
$string = '中國是我的家';
$encrypted = rot13encrypt ($string); // produces 5Yvg5MlY5cvi5bvE55dR5n62
$decrypted = rot13decrypt ($encrypted); // produces 中國是我的家
?>
grawity+phpnet at gmail dot com
31-Dec-2007 10:39
31-Dec-2007 10:39
resubmitting updated function in re:#76975
<?php
function asc_shift($str,$offset=0) {
$new = '';
for ($i = 0; $i < strlen($str); $i++)
$new .= chr(ord($str[$i])+$offset);
return $new;
}
?>
because as of PHP 6, $str{$i} is deprecated.
nick at lazy-river dot net
09-Aug-2007 01:01
09-Aug-2007 01:01
This is recursive function to shift the component letters of a string left or right in the ascii table.
I've left it simple as it suits my needs, but you may want to include error checking for a null string and also put bounds in place, or make it actually rotate around the whole character set rather than just shifting the string up or down.
function asc_shift($string, $amount) {
$key = substr($string, 0, 1);
if(strlen($string)==1) {
return chr(ord($key) + $amount);
} else {
return chr(ord($key) + $amount) . asc_shift(substr($string, 1, strlen($string)-1), $amount);
}
}
For example:
<?php
echo asc_shift("TESTING12345@", 5);
?>
shifts every character up 5 ascii positions, resulting in this string:
YJXYNSL6789:E
In reverse:
<?php
echo asc_shift("YJXYNSL6789:E", -5);
?>
shifts every character down 5 ascii positions, resulting in this string:
TESTING12345@
arwab at surrealwebs dot com
12-Jul-2007 05:11
12-Jul-2007 05:11
here's my rot function, it works anyway
<?php
/**
* preforms the rotation algorithm on the passed in string
*/
function _rot( $str , $dist=13 ){
if( !is_numeric($dist) || $dist < 0){
$dist = 13;
}
$u_lower = 65; $u_upper = 90;
$l_lower = 97; $l_upper = 122;
$char_count = ($u_upper - $u_lower) +1;
while( $dist > $char_count ){
$dist -= $char_count;
}
$newstr = '';
for( $i=0; $i<strlen($str); ++$i){
$c = ord($str[$i]);
/*
* Check if the character is within the bounds of our function (a-zA-z)
* if not it gets tacked on to the string as is and we move on to the
* next one.
*/
if( $c<$u_lower || $c>$l_upper || ( $c>$u_upper && $c <$l_lower ) ){
$newstr .= chr($c);
continue;
}
$lower = ( $c<=$u_upper?$u_lower:$l_lower);
$upper = ( $c<=$u_upper?$u_upper:$l_upper);
$c += $dist;
if( $c > $upper){
$c = (($c - $upper) + ($lower-1));
}
$newstr .= chr($c);
}
return $newstr;
}
?>
electro at whatever dot com
01-Jun-2007 04:21
01-Jun-2007 04:21
<?php
/**
* Rotate each string characters by n positions in ASCII table
* To encode use positive n, to decode - negative.
* With n = 13 (ROT13), encode and decode n can be positive.
*
* @param string $string
* @param integer $n
* @return string
*/
function rotate($string, $n) {
$length = strlen($string);
$result = '';
for($i = 0; $i < $length; $i++) {
$ascii = ord($string{$i});
$rotated = $ascii;
if ($ascii > 64 && $ascii < 91) {
$rotated += $n;
$rotated > 90 && $rotated += -90 + 64;
$rotated < 65 && $rotated += -64 + 90;
} elseif ($ascii > 96 && $ascii < 123) {
$rotated += $n;
$rotated > 122 && $rotated += -122 + 96;
$rotated < 97 && $rotated += -96 + 122;
}
$result .= chr($rotated);
}
return $result;
}
$enc = rotate('string', 6);
echo "Encoded: $enc<br/>\n";
echo 'Decoded: ' . rotate($enc, -6);
?>
maximius at gmail dot com
26-May-2007 08:30
26-May-2007 08:30
Perhaps someone will find this useful ;)
<?
function rotN($s, $n){
$s2 = "";
for($i = 0; $i < strlen($s); $i++){
$char2 = $char = ord($s{$i});
$cap = $char & 32;
$char &= ~ $cap;
$char = $char > 64 && $char < 123 ? (($char - 65 + $n) % 26 + 65) : $char;
$char |= $cap;
if($char < 65 && $char2 > 64 || ($char > 90 && $char < 97 && ($char2 < 91 || $char2 > 96))) $char += 26;
else if($char > 122 && $char2 < 123) $char -= 52;
if(strtoupper(chr($char2)) === chr($char2)) $char = strtoupper(chr($char)); else $char = strtolower(chr($char));
$s2 .= $char;
}
return $s2;
}
?>
It takes any string, $s, and any ROT value, $n. Just like str_rot13, it's both an encoder and decoder. To decode an encoded string, just pass -$n instead of $n.