regex(3)
NAME
re_comp, re_exec − regular expression handler
SYNTAX
char *re_comp(s)
char *s;
int 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, it returns a string containing an error message. If re_comp is passed 0 or a null string, it returns without changing the currently compiled regular expression.
The re_exec returns a 1 if the string s matches the last compiled regular expression, a 0 if the string s failed to match the last compiled regular expression, or a -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(1), 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 \).