Lynn Allan wrote:
Eric Niebler wrote:
Lynn Allan wrote:
The subsequent searches give valid information about the length and position, but other fields in the smatch:what variable seem invalid. regex_search( altDow.substr(32), what, rex) regex_search( altDow.substr(45), what, rex)
Watch out! altDow.substr(32) is returning a temporary string object. After regex_search returns, the temporary is destroyed and the results object is left holding iterators into a destroyed string.
Arggggg. Trying to get "up to speed" with Boost is probably a flawed thing to try to do at the same time as learning rudimentary aspects of STL. "We're not in MFC-land any more, Toto." <g>
std::string altDow32 = altDow.substr(32); if( regex_search( altDow32, what, rex ) ) { unpack }
A better approach would be to use iterators. // Begin searching 32 characters into altDow regex_search( altDow.begin() + 32, altDow.end(), what, rex ) Note #1: the match results will now contain iterators into altDow, but position offsets will be relative to the start of the search, not the start of altDow. Note #2: this code is only valid if altDow has at least 32 characters. Error checking is left as an exercise. :-) Incidentally, your earlier mistake was distressingly easy to make. I can think of a way I might be able to catch this mistake at compile time in a future versions of xpressive. -- Eric Niebler Boost Consulting www.boost-consulting.com