Perform a regular expression search and replace using callbacks
Syntax
preg_replace_callback_array ( array $patterns_and_callbacks , mixed $subject [, int $limit = -1 [, int &$count [, int $flags = 0 ]]] ) : mixed
Parameters
patterns_and_callbacksAn associative array mapping patterns (keys) to callbacks (values).
subjectThe string or an array with strings to search and replace.
limitThe maximum possible replacements for each pattern in each subject string. Defaults to -1 (no limit).
countIf specified, this variable will be filled with the number of replacements done.
flagsflags can be a combination of the PREG_OFFSET_CAPTURE and PREG_UNMATCHED_AS_NULL flags, which influence the format of the matches array.
| PREG_OFFSET_CAPTURE | For every occurring match the appendant string offset (in bytes) will also be returned. Note that this changes the value of matches into an array where every element is an array consisting of the matched string at offset 0 and its string offset into subject at offset 1. |
| PREG_UNMATCHED_AS_NULL | Unmatched subpatterns are reported as NULL; otherwise they are reported as an empty string. |
Return
preg_replace_callback_array() returns an array if the subject parameter is an array, or a string otherwise. On errors the return value is NULL.
If matches are found, the new subject will be returned, otherwise subject will be returned unchanged.
Examples
1 · patterns_and_callbacks subject
<?
function myfunction($matches)
{
return date("Y") . "-" . $matches[1] . "-" . $matches[2];
}
$pattern = "#(\d{2})/(\d{2})/(\d{4})#";
$callback = "myfunction";
$patterns_and_callbacks = array($pattern => $callback);
$subject = "New Years Day: 01/01/2001\n";
$subject .= "Christmas Eve: 12/24/2001\n";
$subject .= "Christmas Day: 12/25/2001\n";
$subject .= "New Years Eve: 12/31/2001";
$return = preg_replace_callback_array($patterns_and_callbacks, $subject);
echo $return;
?>New Years Day: 2023-01-01 Christmas Eve: 2023-12-24 Christmas Day: 2023-12-25 New Years Eve: 2023-12-31
2 · limit
<?
function myfunction($matches)
{
return date("Y") . "-" . $matches[1] . "-" . $matches[2];
}
$pattern = "#(\d{2})/(\d{2})/(\d{4})#";
$callback = "myfunction";
$patterns_and_callbacks = array($pattern => $callback);
$subject = "New Years Day: 01/01/2001\n";
$subject .= "Christmas Eve: 12/24/2001\n";
$subject .= "Christmas Day: 12/25/2001\n";
$subject .= "New Years Eve: 12/31/2001";
$limit = 2;
$return = preg_replace_callback_array($patterns_and_callbacks, $subject, $limit);
echo $return;
?>New Years Day: 2023-01-01 Christmas Eve: 2023-12-24 Christmas Day: 12/25/2001 New Years Eve: 12/31/2001
3 · count
<?
function myfunction($matches)
{
return date("Y") . "-" . $matches[1] . "-" . $matches[2];
}
$pattern = "#(\d{2})/(\d{2})/(\d{4})#";
$callback = "myfunction";
$patterns_and_callbacks = array($pattern => $callback);
$subject = "New Years Day: 01/01/2001\n";
$subject .= "Christmas Eve: 12/24/2001\n";
$subject .= "Christmas Day: 12/25/2001\n";
$subject .= "New Years Eve: 12/31/2001";
$limit = -1;
$return = preg_replace_callback_array($patterns_and_callbacks, $subject, $limit, $count);
echo $return . PHP_EOL;
echo $count;
?>New Years Day: 2023-01-01 Christmas Eve: 2023-12-24 Christmas Day: 2023-12-25 New Years Eve: 2023-12-31 4
4 · flags · PREG_OFFSET_CAPTURE
<?
function myfunction($matches)
{
return date("Y") . "-" . $matches[1][0] . "-" . $matches[2][0] . " (" . $matches[3][1] . " " . $matches[1][1] . " " . $matches[2][1] . ")";
}
$pattern = "#(\d{2})/(\d{2})/(\d{4})#";
$callback = "myfunction";
$patterns_and_callbacks = array($pattern => $callback);
$subject = "New Years Day: 01/01/2001\n";
$subject .= "Christmas Eve: 12/24/2001\n";
$subject .= "Christmas Day: 12/25/2001\n";
$subject .= "New Years Eve: 12/31/2001";
$limit = -1;
$flags = PREG_OFFSET_CAPTURE;
$return = preg_replace_callback_array($patterns_and_callbacks, $subject, $limit, $count, $flags);
echo $return;
?>New Years Day: 2023-01-01 (21 15 18) Christmas Eve: 2023-12-24 (47 41 44) Christmas Day: 2023-12-25 (73 67 70) New Years Eve: 2023-12-31 (99 93 96)
5 · flags · PREG_UNMATCHED_AS_NULL
<?
function myfunction($matches)
{
var_export($matches[1]);
echo " ";
var_export($matches[2]);
echo " ";
var_export($matches[3]);
echo PHP_EOL;
$return = date("Y");
if ($matches[1]) {
$return .= "-" . $matches[1];
}
if ($matches[2]) {
$return .= "-" . $matches[2];
}
return $return;
}
$pattern = "#(\d{2})?/?(\d{2})?/?(\d{4})#";
$callback = "myfunction";
$patterns_and_callbacks = array($pattern => $callback);
$subject = "New Years Day: 2001\n";
$subject .= "Christmas Eve: 12/24/2001\n";
$subject .= "Christmas Day: 12/25/2001\n";
$subject .= "New Years Eve: 2001";
$limit = -1;
$flags = PREG_UNMATCHED_AS_NULL;
$return = preg_replace_callback_array($patterns_and_callbacks, $subject, $limit, $count, $flags);
echo $return;
?>NULL NULL '2001' '12' '24' '2001' '12' '25' '2001' NULL NULL '2001' New Years Day: 2023 Christmas Eve: 2023-12-24 Christmas Day: 2023-12-25 New Years Eve: 2023
6 · Multiple
<?
function myfunction1($matches)
{
return $matches[0][1] . ": " . strlen($matches[0]) . PHP_EOL;
}
function myfunction2($matches)
{
return $matches[0][1] . ": " . $matches[0] . PHP_EOL;
}
$pattern1 = "#[a]+#i";
$pattern2 = "#[b]+#i";
$pattern3 = "#[c]+#i";
$pattern4 = "#[d]+#i";
$callback1 = "myfunction1";
$callback2 = "myfunction2";
$patterns_and_callbacks = array($pattern1 => $callback1, $pattern2 => $callback1, $pattern3 => $callback2, $pattern4 => $callback2);
$subject = "AaaAaaAaaAaa BbbBbbBbb CccCcc Ddd";
$return = preg_replace_callback_array($patterns_and_callbacks, $subject);
echo $return;
?>a: 12 b: 9 c: CccCcc d: Ddd
