boost::regex example runs error throwing an instance of 'std::bad_alloc'

[willzhou42]

Here is the example -

#include <cstdlib>
#include <stdlib.h>
#include <boost/regex.hpp>
#include <string>
#include <iostream>
using namespace std;
using namespace boost;
regex expression ("^select ([a-zA-Z]*) from ([a-zA-Z]*)");
int
main (int argc, char *argv[])
{
    std::string in;
    cmatch what;
    cout << "enter test string" << endl;
    getline (cin, in);
    if (regex_match (in.c_str (), what, expression))
    {
        for (int i = 0; i < what.size (); i++)
            cout << "str :" << what[i].str () << endl;
    }
    else
    {
        cout << "Error Input" << endl;
    }
    return 0;
}

Compiling:

g++ -DBOOST_REGEX_MATCH_EXTRA exp_test.cpp -lboost_regex -o exp_test

Running

will@tp:~/rnd/boost/boost.regex$ ./exp_test
enter test string
select name from users
terminate called after throwing an instance of 'std::bad_alloc'
what(): std::bad_alloc
Aborted
will@tp:~/rnd/boost/boost.regex$


Does anyone know why? Thank you very much.