preg_replace_callback Perform a regular expression search and replace using a callback mixedpreg_replace_callback mixedpattern callbackcallback mixedsubject intlimit The behavior of this function is almost identical to preg_replace, except for the fact that instead of replacement parameter, one should specify a callback that will be called and passed an array of matched elements in the subject string. The callback should return the replacement string. See also preg_replace.