regex(3)
NAME
re_comp, re_exec − regular expression handler
SYNTAX
char *re_comp(s)
char *s;
re_exec(s)
char *s;
DESCRIPTION
The re_comp subroutine compiles a string into an internal form suitable for pattern matching. The re_exec subroutine checks the argument string against the last string passed to re_comp.
The re_comp subroutine returns 0 if the string s was compiled successfully; 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.
The re_exec subroutine 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 nulls. The regular expressions recognized are described in the manual entry for ed(,), given the above difference.
DIAGNOSTICS
The re_exec subroutine returns −1 for an internal error.
The re_comp subroutine returns one of the following strings if an error occurs:
No previous regular expression
Regular expression too long
unmatched \(
missing ]
too many \(\) pairs
unmatched \)