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chr

(PHP 4, PHP 5, PHP 7, PHP 8)

chr从数字生成单字节字符串

说明

chr(int $codepoint): string

返回单字符字符串,包含将 codepoint 作为无符号整数解释的指定字符。

这可用于在一种单字节编码(像是 ASCII、ISO-8859 或 Windows 1252)中通过传递想要的字符在编码映射表中的位置来创建单字符字符串。但是,注意此函数并不清楚任何字符串编码,特别是无法通过传递一个 Unicode 码位值来生成多字节编码(像是 UTF-8 或 UTF-16)字符串。

此函数与 ord() 互补。

参数

codepoint

一个介于 0 与 255 之间的整数。

超过有效范围(0..255)的值将和 255“按位与”,与以下算法等效:

while ($bytevalue < 0) {
$bytevalue += 256;
}
$bytevalue %= 256;

返回值

包含指定字节的单字符字符串。

更新日志

版本 说明
7.4.0 此函数不再静默接受不支持的 codepoint,并会将它们转为 0

示例

示例 #1 chr() 例子

<?php
// 假设该字符串将被作为 ASCII 或是一个与 ASCII 兼容的编码使用

$str = "The string ends in escape: ";
$str .= chr(27); /* 在 $str 末尾添加一个转义字符 */

/* 通常这样更有用 */

$str = sprintf("The string ends in escape: %c", 27);
?>

示例 #2 溢出行为

<?php
echo chr(-159), chr(833), PHP_EOL;
?>

以上示例会输出:

aA

示例 #3 从单个字节构建 UTF-8 字符串

<?php
$str
= chr(240) . chr(159) . chr(144) . chr(152);
echo
$str;
?>

以上示例会输出:


🐘

参见

  • sprintf() - 返回格式化字符串 如何使用格式字符串 %c
  • ord() - 转换字符串第一个字节为 0-255 之间的值
  • 一个 » ASCII 表
  • mb_chr() - 按 Unicode 码位值返回字符
  • IntlChar::chr() - Return Unicode character by code point value

add a note

User Contributed Notes 23 notes

up
21
perrodin at laposte dot net
19 years ago
Note that if the number is higher than 256, it will return the number mod 256.
For example :
chr(321)=A because A=65(256)
up
14
voromax
15 years ago
Another quick and short function to get unicode char by its code.

<?php
/**
* Return unicode char by its code
*
* @param int $u
* @return char
*/
function unichr($u) {
return
mb_convert_encoding('&#' . intval($u) . ';', 'UTF-8', 'HTML-ENTITIES');
}
?>
up
7
grey - greywyvern - com
18 years ago
I spent hours looking for a function which would take a numeric HTML entity value and output the appropriate UTF-8 bytes. I found this at another site and only had to modify it slightly; so I don't take credit for this.

<?php function unichr($dec) {
if (
$dec < 128) {
$utf = chr($dec);
} else if (
$dec < 2048) {
$utf = chr(192 + (($dec - ($dec % 64)) / 64));
$utf .= chr(128 + ($dec % 64));
} else {
$utf = chr(224 + (($dec - ($dec % 4096)) / 4096));
$utf .= chr(128 + ((($dec % 4096) - ($dec % 64)) / 64));
$utf .= chr(128 + ($dec % 64));
}
return
$utf;
}
?>

So for example:

<?php

$str
= "Chinese: &#20013;&#25991;";
$str = preg_replace("/&#(\d{2,5});/e", "unichr($1);", $str);

?>
up
4
Noname
2 years ago
<?php

for ($i = 128; $i <= 191; $i++) {
$str = chr(240) . chr(159) . chr(144) . chr($i);
echo
$str;
}

?>
up
4
mailderemi at gmail dot com
13 years ago
Here is a sample of encoding and decoding using "chr" and "ord".
<?php
function Encode($txtData,$Level){
for (
$j = 0;$j<$Level;$j++){
$tmpStr = '';
for (
$i = 0;$i<strlen($txtData);$i++)
$tmpStr .= ord(substr(strtoupper($txtData), $i, 1));
$txtData = $tmpStr;
}
return (
strlen($Level)).$Level.$txtData;
}

function
Decode($txtData){
$intLevel = substr($txtData, 1, substr($txtData, 0, 1));
$startStr = substr($txtData, substr($txtData, 0, 1)+1, strlen($txtData));
for (
$j = 0;$j<$intLevel;$j++){
for (
$i = 0;$i<strlen($startStr);$i+=2)
$tmpStr .= chr(intval(substr($startStr, $i, 2)));
$startStr = $tmpStr;

$tmpStr = "";
}
return
$startStr;
}

echo
Encode('123',4).'<br>';
echo
Decode(Encode('123',5));
?>
up
2
synnus at gmail dot com
8 years ago
// rivencodec 1.0
// encode riverse ascii 1 simple function can encode/decode
// can use it for secure source with speed encode text

<?php

function rivencodec($ch,$a=0) {
while((@
$b = $ch[$a++])) { $ch[$a-1] = chr(255-ord($b)); }
return
$ch;
}


$zz = rivencodec("abcdefghijklmn");
echo
'encode: ',$zz,'<br/>',PHP_EOL;

$yy = rivencodec($zz);
echo
'decode: ',$yy,'<br/>',PHP_EOL;

?>
up
2
joeldegan AT yahoo.com
21 years ago
Want terminal colors in command line php scripts?

This should take care of that.
<?

$_colors = array(
'LIGHT_RED' => "[1;31m",
'LIGHT_GREEN' => "[1;32m",
'YELLOW' => "[1;33m",
'LIGHT_BLUE' => "[1;34m",
'MAGENTA' => "[1;35m",
'LIGHT_CYAN' => "[1;36m",
'WHITE' => "[1;37m",
'NORMAL' => "[0m",
'BLACK' => "[0;30m",
'RED' => "[0;31m",
'GREEN' => "[0;32m",
'BROWN' => "[0;33m",
'BLUE' => "[0;34m",
'CYAN' => "[0;36m",
'BOLD' => "[1m",
'UNDERSCORE' => "[4m",
'REVERSE' => "[7m",

);

function termcolored($text, $color="NORMAL", $back=1){
global $_colors;
$out = $_colors["$color"];
if($out == ""){ $out = "[0m"; }
if($back){
return chr(27)."$out$text".chr(27).chr(27)."[0m".chr(27);
}else{
echo chr(27)."$out$text".chr(27).chr(27)."[0m".chr(27);
}//fi
}// end function

echo termcolored("test\n", "BLUE");
?>
up
1
scott at quinlan dot co dot nz
15 years ago
Secure password generator with a variable maximum amount of symbols.

<?php

function passwdGen($minLength = 8, $maxLength = 12, $maxSymbols = 2)
{
$symbolCount = 0;

srand((double)microtime() * 1000003);

for (
$i = 0; $i < rand($minLength, $maxLength); $i++)
{
do
{
$char = rand(33, 126);

$symbolCount += $isSymbol = (!in_array($char, range(48, 57)) && !in_array($char, range(65, 90)) && !in_array($char, range(97, 122)));

if (
$symbolCount <= $maxSymbols || !$isSymbol)
{
break;
}
}
while (
true);

$passwd = sprintf('%s%c', isset($passwd) ? $passwd : NULL, $char);
}

return
$passwd;
}

?>
up
1
happyevil(at)1218.org
22 years ago
Here is a function that's help me find what chr(number) outputs what character quicker than typing out 256 echo tags.

<?php
function listChr(){
for (
$i = 0; $i < 256; ++$i) {
static
$genNum;
$genNum++;
echo
"chr($genNum) will output '";
echo (
chr($genNum));
echo
"'< br>\n";
}
}
listChr();
?>

Another helpful chr is #9, being a tab. Quite using when making error logs.

$tab = (chr(9));
echo "<pre>error{$tab}date{$tab}time</pre>";

-- HappyEvil
up
0
gjarrige at six-axe dot fr
12 years ago
to remove the ASCII control characters (except "line feed" and "tab") :

$tab_chr = array() ;
for($control = 0; $control < 32; $control++) {
if ($control != 9 && $control != 10) {
$tab_chr[]= chr($control) ;
}
}
$tab_chr[]= chr(127) ;
$string = str_replace($tab_chr, '', $string);
up
0
Josh B.
15 years ago
In addition to replacing Microsoft Windows smart quotes, as sgaston demonstrated on 2006-02-13, I replace all other Microsoft Windows characters using suggestions[1] published by character code specialist[2] Jukka Korpela.

<?php
$str
= str_replace(chr(130), ',', $str); // baseline single quote
$str = str_replace(chr(131), 'NLG', $str); // florin
$str = str_replace(chr(132), '"', $str); // baseline double quote
$str = str_replace(chr(133), '...', $str); // ellipsis
$str = str_replace(chr(134), '**', $str); // dagger (a second footnote)
$str = str_replace(chr(135), '***', $str); // double dagger (a third footnote)
$str = str_replace(chr(136), '^', $str); // circumflex accent
$str = str_replace(chr(137), 'o/oo', $str); // permile
$str = str_replace(chr(138), 'Sh', $str); // S Hacek
$str = str_replace(chr(139), '<', $str); // left single guillemet
$str = str_replace(chr(140), 'OE', $str); // OE ligature
$str = str_replace(chr(145), "'", $str); // left single quote
$str = str_replace(chr(146), "'", $str); // right single quote
$str = str_replace(chr(147), '"', $str); // left double quote
$str = str_replace(chr(148), '"', $str); // right double quote
$str = str_replace(chr(149), '-', $str); // bullet
$str = str_replace(chr(150), '-', $str); // endash
$str = str_replace(chr(151), '--', $str); // emdash
$str = str_replace(chr(152), '~', $str); // tilde accent
$str = str_replace(chr(153), '(TM)', $str); // trademark ligature
$str = str_replace(chr(154), 'sh', $str); // s Hacek
$str = str_replace(chr(155), '>', $str); // right single guillemet
$str = str_replace(chr(156), 'oe', $str); // oe ligature
$str = str_replace(chr(159), 'Y', $str); // Y Dieresis
?>

[1] On the use of some MS Windows characters in HTML
http://www.cs.tut.fi/~jkorpela/www/windows-chars.html

[2] Unicode Explained by Jukka Korpela
http://www.amazon.com/dp/059610121X/
up
0
tenyou at gmail dot com
19 years ago
When having to deal with parsing an IIS4 or IIS5 metabase dump I wrote a simple function for converting those MS hexidecimal values into their ascii counter parts. Hopefully someone will find use for it.

<?php
function hex_decode($string) {
for (
$i=0; $i < strlen($string); $i) {
$decoded .= chr(hexdec(substr($string,$i,2)));
$i = (float)($i)+2;
}
return
$decoded;
}
?>
up
-1
darek at module17 dot com
11 years ago
Simple password generation function using sprintf and the %c type specifier; which is the same as chr().

function genPass($len = 8) {
for ($i=0;$i<=$len;$i++) {
$passwd = sprintf('%s%c', isset($passwd) ? $passwd : NULL, rand(48, 122));
}
return $passwd;
}
up
-1
Kristin
21 years ago
Note that chr(10) is a 'line feed' and chr(13) is a 'carriage return' and they are not the same thing! I found this out while attempting to parse text from forms and text files for inclusion as HTML by replacing all the carriage returns with <BR>'s only to find after many head-scratchings that I should have been looking for line feeds. If anyone can shed some light on what the difference is, please do.

If you're planning on saving text from a form into a database for later display, you'll need to apply the following function so that it gets saved with the proper HTML tags.

<?php
$text
= str_replace ( chr(10), "<BR>", $text );
?>

When you want to plug it back into that form for editing you need to convert it back.

<?php
$text
= str_replace ( "<BR>", chr(10), $text)
?>

Hope this saves somebody some trouble. :)
up
-1
v14t at gmx dot com
9 years ago
argument is automatically converted to integer, so chr('65') and chr(65) would both output the letter A
up
-1
ddawsonNOSPAM at execpc dot com
23 years ago
[Editor's note:

%c is defined as: "Print the character belonging to the ascii code given"

chr() just gives a string, so you need to use %s, even if the string consists of only one character. This is consistent with other languages.
--Jeroen@php.net]


Learn from my mistake:
Do not expect this to work!

<?php
$c_question
= chr(63);
$v_out = sprintf("<%cphp\n", $c_question);
//... more stuff being sprintf'd into v_out here ...
$v_out = sprintf("%s%c>\n", $v_out, $c_question);
$v_fp = fopen("foofile", "w");
if (
$v_fp)
{
fwrite($v_fp, $v_out, strlen($v_out));
fclose($v_fp);
}
?>

When I did this, foofile contained <NUL NUL NUL NUL NUL>.
I spun my wheels quite awhile looking at fputs, fwrite to verify I was calling those functions correctly.
My mistake was using $c_question = chr(63) instead of
$c_question = 63 (correct). Then everything worked fine.
up
-2
vitkorob
8 years ago
Another quick function to get unicode char by its code.

<?php

function unichr($dec)
{
if (
$dec < 0x80)
{
$utf = chr($dec);
}
else if (
$dec < 0x0800)
{
$utf = chr(0xC0 + ($dec >> 6));
$utf .= chr(0x80 + ($dec & 0x3f));
}
else if (
$dec < 0x010000)
{
$utf = chr(0xE0 + ($dec >> 12));
$utf .= chr(0x80 + (($dec >> 6) & 0x3f));
$utf .= chr(0x80 + ($dec & 0x3f));
}
else if (
$dec < 0x200000)
{
$utf = chr(0xF0 + ($dec >> 18));
$utf .= chr(0x80 + (($dec >> 12) & 0x3f));
$utf .= chr(0x80 + (($dec >> 6) & 0x3f));
$utf .= chr(0x80 + ($dec & 0x3f));
}
else
{
die(
"UTF-8 character size is more than 4 bytes");
}

return
$utf;
}

echo
unichr(0x263A);

?>
up
-2
Ray.Paseur sometimes uses Gmail
5 years ago
I needed to generate an invalid UTF-8 character for testing with JSON. This did the trick:

<?php
echo 'Bogus UTF-8 character at end' . chr(0xC6) ;
up
-2
ibaid at mail dot ru
5 years ago
string mb_chr ( int $cp [, string $encoding ] )
Parameter List:
cp - character code (in decimal notation)
encoding - encoding (UTF-8, ASCII and so on)

We get the letter 'Ж' from the encoding UTF-8:

$sim = mb_chr(0x0416, 'UTF-8');
echo $sim; // Ж

Get the character '}' from the encoding ASCII:

$sim = mb_chr(125, 'ASCII');
echo $sim ; // }
up
-4
darkodemon at gmail dot com
16 years ago
chr() with unicode support

<?php

function uchr ($codes) {
if (
is_scalar($codes)) $codes= func_get_args();
$str= '';
foreach (
$codes as $code) $str.= html_entity_decode('&#'.$code.';',ENT_NOQUOTES,'UTF-8');
return
$str;
}

echo
uchr(23383); echo '<br/>';
echo
uchr(23383,215,23383); echo '<br/>';
echo
uchr(array(23383,215,23383,215,23383)); echo '<br/>';

?>
up
-3
sinfocol at sinfocol dot org
14 years ago
The function chr() also accepts negative numbers as an ascii code, so chr(-number) is equal to chr((number%256)+256).
And for ascii code higher than 255 is chr(number%256)

We can test with a little script
<?php
for($i=-300; $i<300; $i++){
echo
"Ascii $i\t" . ord(chr($i)) . "\n";
}
?>
up
-5
lingtalfi - at - somewhere
8 years ago
It seems that php uses the table from here: http://ascii-code.com/
(and not from here: http://www.asciitable.com/ as suggested in the documentation) for codes from 128 to 255.

<?php
for ($i = 32; $i <= 255; $i++) {
echo
chr($i);
}
?>
up
-3
gfour
4 years ago
I was looking for a simple method to construct excel like column identifiers e.g: A B .... AA AB AC etc, using chr() and modulo, but there is magic...
https://www.php.net/manual/en/language.operators.increment.php

So, this also works
<?php
$p
= chr(65); // or simply $p = 'A';
for ($i = 1; $i < 53; $i++){
echo
$p++ . " - ";
if (
$i % 10 == 0) echo '</br>';
}
?>

Gives
A - B - C - D - E - F - G - H - I - J -
K - L - M - N - O - P - Q - R - S - T -
U - V - W - X - Y - Z - AA - AB - AC - AD -
AE - AF - AG - AH - AI - AJ - AK - AL - AM - AN -
AO - AP - AQ - AR - AS - AT - AU - AV - AW - AX -
AY - AZ -
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