boost xpressive: wrong match?

Question

I want to match a simple expression with boost, but it behaves strange... The code below should match and display "a" from first and second strings:

#include <iostream>
#include <boost/xpressive/xpressive.hpp>

#include "stdio.h"

using namespace boost::xpressive;

void xmatch_action( const char *line ) {
    cregex g_re_var;
    cmatch what;
    g_re_var = cregex::compile( "\\s*var\\s+([\\w]+)\\s*=.*?" );


    if (regex_match(line, what, g_re_var )) {
        printf("OK\n");
        printf(">%s<\n", what[1] );
    }
    else {
        printf("NOK\n");
    }
}

int main()
{
    xmatch_action("var a = qqq");
    xmatch_action(" var a = aaa");
    xmatch_action(" var abc ");
}

but my actual output is:

OK
>a = qqq<
OK
>a = aaa<
NOK

and it should be

OK
>a<
OK
>a<
NOK

score 1 · Accepted Answer · answered Jun 26 '11 at 02:36

1

Instead of printf() use the << operator to print the sub_match object (what[1]). Or you can try using what[1].str() instead of what[1].

See the docs: sub_match, match_results, regex_match

answered Jun 26 '11 at 02:36

Qtax

33,241
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results of a small test; those are OK: `cout << what[1] << endl; printf("%s\n", what[1].str().c_str() ); printf("%s\n", string(what[1]).c_str() );` This is not OK: `printf("%s\n", what[1] );` – Jakub M. Jun 26 '11 at 10:01

Leonid Volnitsky · Answer 2 · 2012-01-14T21:35:34.483

0

Remove square brackets around \w in regex AND use std::cout for printing. Then you will get result that you want.

edited Jan 14 '12 at 21:35

answered Jan 14 '12 at 21:24

Leonid Volnitsky

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boost xpressive: wrong match?

2 Answers2