What are PHP Regular Expression Functions?

1. preg_match() ---> The preg_match() function searches string for pattern, returning true if pattern exists, and false otherwise.
2. preg_match_all() ---> The preg_match_all() function matches all occurrences of pattern in string.
3. preg_replace() ---> The preg_replace() function operates just like ereg_replace(), except that regular expressions can be used in the pattern and replacement input parameters.
4. preg_split() ---> The preg_split() function operates exactly like split(), except that regular expressions are accepted as input parameters for pattern.
5. preg_grep() ---> The preg_grep() function searches all elements of input_array, returning all elements matching the regexp pattern.
6. preg_ quote() ---> Quote regular expression characters