REGEX(3) Library Functions Manual REGEX(3)
regex, re_comp, re_exec - regular expression handler
re_comp() compiles a string into an internal form suitable for pattern
matching. re_exec() checks the argument string against the last string
passed to re_comp().
re_comp() returns a NULL pointer if the string s was compiled success-
fully; otherwise a string containing an error message is returned. If
re_comp() is passed 0 or a null string, it returns without changing the
currently compiled regular expression.
re_exec() returns 1 if the string s matches the last compiled regular
expression, 0 if the string s failed to match the last compiled regular
expression, and -1 if the compiled regular expression was invalid
(indicating an internal error).
The strings passed to both re_comp() and re_exec() may have trailing or
embedded NEWLINE characters; they are terminated by null characters.
The regular expressions recognized are described in the manual entry
for ed(1), given the above difference.
ed(1), ex(1), grep(1V)
re_exec() returns -1 for an internal error.
re_comp() returns one of the following strings if an error occurs:
No previous regular expression
Regular expression too long
too many \(\) pairs
6 October 1987 REGEX(3)