The string or an array with strings to replace. If this parameter is a string and the
patternparameter is an array, all patterns will be replaced by that string. If both
replacementparameters are arrays, each
patternwill be replaced by the
replacementcounterpart. If there are fewer elements in the
replacementarray than in the
patternarray, any extra
patterns will be replaced by an empty string.
replacementmay contain references of the form \n or (since PHP 4.0.4) $n, with the latter form being the preferred one. Every such reference will be replaced by the text captured by the n‘th parenthesized pattern. n can be from 0 to 99, and \0 or refers to the text matched by the whole pattern. Opening parentheses are counted from left to right (starting from 1) to obtain the number of the capturing subpattern. To use backslash in replacement, it must be doubled (“\\” PHP string).
When working with a replacement pattern where a backreference is immediately followed by another number (i.e.: placing a literal number immediately after a matched pattern), you cannot use the familiar \1 notation for your backreference. \11, for example, would confuse preg_replace() since it does not know whether you want the \1 backreference followed by a literal 1, or the \11 backreference followed by nothing. In this case the solution is to use 1. This creates an isolated backreference, leaving the 1 as a literal.
When using the deprecated e modifier, this function escapes some characters (namely‘, “, \ and NULL) in the strings that replace the backreferences. This is done to ensure that no syntax errors arise from backreference usage with either single or double quotes (e.g.‘strlen(\’\’)+strlen(“”)’). Make sure you are aware of PHP’sstring syntax to know exactly how the interpreted string will look.
The string or an array with strings to search and replace.
subjectis an array, then the search and replace is performed on every entry of
subject, and the return value is an array as well.
The maximum possible replacements for each pattern in each
subjectstring. Defaults to -1 (no limit).
If specified, this variable will be filled with the number of replacements done.
Return Values ¶
preg_replace() returns an array if the
subject parameter is an array, or a string otherwise.
If matches are found, the new
subject will be returned, otherwise
subject will be returned unchanged or
NULL if an error occurred.
As of PHP 5.5.0
E_DEPRECATED level error is emitted when passing in the “\e” modifier. As of PHP 7.0.0
E_WARNING is emited in this case and “\e” modifier has no effect.
|7.0.0||Support for the /e modifier has been removed. Use preg_replace_callback()instead.|
|5.5.0||The /e modifier is deprecated. Use preg_replace_callback() instead. See thePREG_REPLACE_EVAL documentation for additional information about security risks.|