09-13-2012
Quote:
Originally Posted by
vgersh99
It's probably a good idea to avoid regular expressions. If the real data can contain regular expression metacharacters, they could lead to an erroneous result. Even if the data is strictly alphabetical (as in the sample data), it might be a little bit faster to just use
index(i,j).
Regards,
Alister
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REGEX(3) Library Functions Manual REGEX(3)
NAME
re_comp, re_exec - regular expression handler
SYNOPSIS
char *re_comp(s)
char *s;
re_exec(s)
char *s;
DESCRIPTION
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 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.
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 nulls. The regular
expressions recognized are described in the manual entry for ed(1), given the above difference.
SEE ALSO
ed(1), ex(1), egrep(1), fgrep(1), grep(1)
DIAGNOSTICS
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,
unmatched (,
missing ],
too many () pairs,
unmatched ).
3rd Berkeley Distribution May 15, 1985 REGEX(3)