Regex match whole string

Question

I have the following pattern:

[ \n\t]*([a-zA-Z][a-zA-Z0-9_]*)[ \n\t]+((char)[ \n\t]*\[[ \n\t]*([0-9]+)[ \t\n]*\]|(char)|(int)|(double)|(bool)|(blob)[ \n\t]*\[[ \n\t]*([0-9]+)[ \t\n]*\])[ \n\t]*

You can try it here: http://regex101.com/r/vA0xG9

In the first capturing group ([a-zA-Z][a-zA-Z0-9_]*), I want to grab words that only starts with a-zA-Z.

The two following strings matches equally:

cpf char[12]

,

9cpf char[12]

It ignores the 9 digit and matches equally to the first string.

I've tried to use this capturing group: (ˆ[a-zA-Z][a-zA-Z0-9_]*$), but it didn't work.

I'm using lib regex.h.

What should I do?

Thanks.

Answer 1

Put ^ at the beginning of the whole thing and $ at the end

^[ \n\t]*([a-zA-Z][a-zA-Z0-9_]*)[ \n\t]+((char)[ \n\t]*\[[ \n\t]*([0-9]+)[ \t\n]*\]|(char)|(int)|(double)|(bool)|(blob)[ \n\t]*\[[ \n\t]*([0-9]+)[ \t\n]*\])[ \n\t]*$

I would also suggest \s instead of [ \n\t] if you want to match whitespace.

Answer 2

In C++, there is a handy regex method that anchors the match to the whole string automatically: std::regex_match:

Determines if the regular expression e matches the entire target character sequence, which may be specified as std::string, a C-string, or an iterator pair.

This way, you will avoid issues with mistyped ^ as ˆ as well as cases when you have alternation (e.g. ^A|B$ won't match strings only equal to A or B, you need ^(A|B)$ or ^(?:A|B)$).

Note that there is an equivalent boost::regex_match method.