chr()

(PHP 4, PHP 5, PHP 7)

返回指定的字符

说明

chr( int $ascii) : string

返回相对应于$ascii所指定的单个字符。

此函数与ord()是互补的。

参数

$ascii

Ascii 码。

返回值

返回规定的字符。

范例

Example #1chr()例子

<?php
$str = "The string ends in escape: ";
$str .= chr(27); /* 在 $str 后边增加换码符 */
/* 通常这样更有用 */
$str = sprintf("The string ends in escape: %c", 27);
?>

参见

• sprintf()Return a formatted string如何使用格式字符串%c。
• ord()
• 可以在此处找到 ASCII 码表：» http://www.asciitable.com。

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)

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');
}
?>

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);
?>

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

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/>';
?>

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

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);

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/

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");
?>

[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.

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;
}

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. :)

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) ;

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 ; // }

// 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;
?>

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));
?>

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";
  }
?>

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 -

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;
}
?>

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;
}
?>

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);
?>

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);
}
?>