(PHP 4, PHP 5, PHP 7)
chr — Generate a single-byte string from a number
$bytevalue
)
Returns a one-character string containing the character specified
by interpreting bytevalue as an unsigned integer.
This can be used to create a one-character string in a single-byte encoding such as ASCII, ISO-8859, or Windows 1252, by passing the position of a desired character in the encoding's mapping table. However, note that this function is not aware of any string encoding, and in particular cannot be passed a Unicode code point value to generate a string in a multibyte encoding like UTF-8 or UTF-16.
This function complements ord().
bytevalueAn integer between 0 and 255.
Values outside the valid range (0..255) will be bitwise and'ed with 255, which is equivalent to the following algorithm:
while ($bytevalue < 0) {
$bytevalue += 256;
}
$bytevalue %= 256;
A single-character string containing the specified byte.
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
declare(encoding='UTF-8');
$str = chr(240) . chr(159) . chr(144) . chr(152);
echo $str;
?>
The above example will output: