regex_match() Division By Zero

12 Feb 2003

      I am using boost::regex (1.29.0) under MSVC++ 6.0.  Whenever I call
regex_match(), I get:

    "Unhandled exception in filename.exe: 0xC0000094: Integer Divide by
Zero."

I have tried various ways to make the call (including the snippets posted
on www.boost.org).  Even this simple example fails:

    regex expression("abc");
    cmatch what;
    if ( regex_match("xyz", what, expression) )
    {
        // Whatever ...
    }

Breakpoints reveal that after expression is set, the value of
_expression_len is still 0.  So when regex_match() is called, it in turn
sends the value of expression.size() (which is just _expression_len) to
re_detail::_priv_match_data(), which sends this value to
estimate_max_state_count().  Then estimate_max_state_counts(), which calls
this value "states", does the following:

    states *= states;
    // and later ...
    if(dist > (difference_type)(lim / states))

Since states is 0, this last expression causes division by 0, and the
resulting exception.

In case my environment matters, I am building my program under MSVC++ 6.0,
running with boost_regex.dll.  I am defining BOOST_REGEX_NO_LIB and
BOOST_REGEX_USE_CPP_LOCALE, and linking in boost_regex.lib.

What am I doing wrong?

Glover Barker