chr

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

chr — Generate a single-byte string from a number

Description

chr(int $codepoint): string

Returns a one-character string containing the character specified by interpreting codepoint as an unsigned integer.

This can be used to create a one-character string in a single-byte encoding such as ASCII, ISO-8859, or Windows 1252, by passing the position of a desired character in the encoding's mapping table. However, note that this function is not aware of any string encoding, and in particular cannot be passed a Unicode code point value to generate a string in a multibyte encoding like UTF-8 or UTF-16.

This function complements ord().

Parameters

codepoint

An integer between 0 and 255.

Values outside the valid range (0..255) will be bitwise and'ed with 255, which is equivalent to the following algorithm:

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

Return Values

A single-character string containing the specified byte.

Changelog

Version	Description
7.4.0	The function no longer silently accepts unsupported `codepoint`s, and casts these to `0`.

Examples

Example #1 chr() example

<?php
// Assumes the string will be used as ASCII or an ASCII-compatible encoding

$str = "The string ends in escape: ";
$str .= chr(27); /* add an escape character at the end of $str */

/* Often this is more useful */

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

Example #2 Overflow behavior

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

The above example will output:

aA

Example #3 Building a UTF-8 string from individual bytes

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

The above example will output:

🐘

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User Contributed Notes 23 notes

down

perrodin at laposte dot net ¶

20 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)

down

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');
}
?>

down

grey - greywyvern - com ¶

19 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);

?>

down

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));
?>

down

Noname ¶

2 years ago

<?php

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

?>

down

synnus at gmail dot com ¶

9 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;

?>

down

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");

?>

down

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);

down

tenyou at gmail dot com ¶

20 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;

}

?>

down

Josh B. ¶

16 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/

down

scott at quinlan dot co dot nz ¶

16 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;
}

?>

down

happyevil(at)1218.org ¶

23 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

down

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) ;

down

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);

?>

down

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;
}

down

ddawsonNOSPAM at execpc dot com ¶

24 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.

down

-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. :)

down

-1

v14t at gmx dot com ¶

10 years ago

argument is automatically converted to integer, so chr('65') and chr(65) would both output the letter A

down

-2

ibaid at mail dot ru ¶

6 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 ; // }

down

-3

lingtalfi - at - somewhere ¶

9 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);
}
?>

down

-4

darkodemon at gmail dot com ¶

17 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/>';

?>

down

-2

gfour ¶

5 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 -

down

-3

sinfocol at sinfocol dot org ¶

15 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";

    }

?>

＋add a note

chr

Description

Parameters

Return Values

Changelog

Examples

See Also

Found A Problem?

User Contributed Notes 23 notes