HASH(3) 1 HASH(3)
hash - Generate a hash value (message digest)
SYNOPSIS
string hash (string $algo, string $data, [bool $raw_output = false])
DESCRIPTION
PARAMETERS
o $algo
- Name of selected hashing algorithm (e.g. "md5", "sha256", "haval160,4", etc..)
o $data
- Message to be hashed.
o $raw_output
- When set to TRUE, outputs raw binary data. FALSE outputs lowercase hexits.
RETURN VALUES
Returns a string containing the calculated message digest as lowercase hexits unless $raw_output is set to true in which case the raw
binary representation of the message digest is returned.
CHANGELOG
+--------+---------------------------------------------------+
|Version | |
| | |
| | Description |
| | |
+--------+---------------------------------------------------+
| 5.4.0 | |
| | |
| | The tiger algorithm now uses big-endian byte |
| | ordering. See also example below. |
| | |
+--------+---------------------------------------------------+
EXAMPLES
Example #1
A hash(3) example
<?php
echo hash('ripemd160', 'The quick brown fox jumped over the lazy dog.');
?>
The above example will output:
ec457d0a974c48d5685a7efa03d137dc8bbde7e3
Example #2
Calculate pre PHP-5.4 tiger hashes with PHP-5.4 and higher
<?php
function old_tiger($data = "", $width=192, $rounds = 3) {
return substr(
implode(
array_map(
function ($h) {
return str_pad(bin2hex(strrev($h)), 16, "0");
},
str_split(hash("tiger192,$rounds", $data, true), 8)
)
),
0, 48-(192-$width)/4
);
}
echo hash('tiger192,3', 'a-string'), PHP_EOL;
echo old_tiger('a-string'), PHP_EOL;
?>
Output of the above example in PHP 5.3:
146a7492719b3564094efe7abbd40a7416fd900179d02773
64359b7192746a14740ad4bb7afe4e097327d0790190fd16
Output of the above example in PHP 5.4:
64359b7192746a14740ad4bb7afe4e097327d0790190fd16
146a7492719b3564094efe7abbd40a7416fd900179d02773
SEE ALSO
hash_file(3), hash_hmac(3), hash_init(3), md5(3), sha1(3).
PHP Documentation Group HASH(3)
Check Out this Related Man Page
SUBSTR(3) 1 SUBSTR(3)
substr - Return part of a string
SYNOPSIS
string substr (string $string, int $start, [int $length])
DESCRIPTION
Returns the portion of $string specified by the $start and $length parameters.
PARAMETERS
o $string
- The input string. Must be one character or longer.
o $start
- If $start is non-negative, the returned string will start at the $start'th position in $string, counting from zero. For
instance, in the string ' abcdef', the character at position 0 is ' a', the character at position 2 is ' c', and so forth. If
$start is negative, the returned string will start at the $start'th character from the end of $string. If $string is less than or
equal to $start characters long, FALSE will be returned.
Example #1
Using a negative $start
<?php
$rest = substr("abcdef", -1); // returns "f"
$rest = substr("abcdef", -2); // returns "ef"
$rest = substr("abcdef", -3, 1); // returns "d"
?>
o $length
- If $length is given and is positive, the string returned will contain at most $length characters beginning from $start (depend-
ing on the length of $string). If $length is given and is negative, then that many characters will be omitted from the end of
$string (after the start position has been calculated when a $start is negative). If $start denotes the position of this trunca-
tion or beyond, false will be returned. If $length is given and is 0, FALSE or NULL, an empty string will be returned. If
$length is omitted, the substring starting from $start until the end of the string will be returned.
Example #2
Using a negative $length
<?php
$rest = substr("abcdef", 0, -1); // returns "abcde"
$rest = substr("abcdef", 2, -1); // returns "cde"
$rest = substr("abcdef", 4, -4); // returns false
$rest = substr("abcdef", -3, -1); // returns "de"
?>
RETURN VALUES
Returns the extracted part of $string; or FALSE on failure, or an empty string.
CHANGELOG
+--------------+---------------------------------------------------+
| Version | |
| | |
| | Description |
| | |
+--------------+---------------------------------------------------+
|5.2.2 - 5.2.6 | |
| | |
| | If the $start parameter indicates the position |
| | of a negative truncation or beyond, false is |
| | returned. Other versions get the string from |
| | start. |
| | |
+--------------+---------------------------------------------------+
EXAMPLES
Example #3
Basic substr(3) usage
<?php
echo substr('abcdef', 1); // bcdef
echo substr('abcdef', 1, 3); // bcd
echo substr('abcdef', 0, 4); // abcd
echo substr('abcdef', 0, 8); // abcdef
echo substr('abcdef', -1, 1); // f
// Accessing single characters in a string
// can also be achieved using "square brackets"
$string = 'abcdef';
echo $string[0]; // a
echo $string[3]; // d
echo $string[strlen($string)-1]; // f
?>
Example #4
substr(3) casting behaviour
<?php
class apple {
public function __toString() {
return "green";
}
}
echo "1) ".var_export(substr("pear", 0, 2), true).PHP_EOL;
echo "2) ".var_export(substr(54321, 0, 2), true).PHP_EOL;
echo "3) ".var_export(substr(new apple(), 0, 2), true).PHP_EOL;
echo "4) ".var_export(substr(true, 0, 1), true).PHP_EOL;
echo "5) ".var_export(substr(false, 0, 1), true).PHP_EOL;
echo "6) ".var_export(substr("", 0, 1), true).PHP_EOL;
echo "7) ".var_export(substr(1.2e3, 0, 4), true).PHP_EOL;
?>
The above example will output:
1) 'pe'
2) '54'
3) 'gr'
4) '1'
5) false
6) false
7) '1200'
ERRORS
/EXCEPTIONS
Returns FALSE on error.
Example #5
<?php
var_dump(substr('a', 1)); // bool(false)
?>
SEE ALSO
strrchr(3), substr_replace(3), preg_match(3), trim(3), mb_substr(3), wordwrap(3), String access and modification by character.
PHP Documentation Group SUBSTR(3)