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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 codepoints, 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 */
echo $str, PHP_EOL;

/* Often this is more useful */
$str = sprintf("The string ends in escape: %c", 27);
echo $str, PHP_EOL;
?>

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, PHP_EOL;
?>

The above example will output:


🐘

See Also