How can I make the map::find operation case insensitive?

Question

Does the map::find method support case insensitive search? I have a map as follows:

map > directory;
<         


        

Answer 1

I'd like to present a short solution without using Boost or templates. Since C++11 you can also provide a lambda expression as custom comparator to your map. For a POSIX-compatible system, the solution could look as follows:

auto comp = [](const std::string& s1, const std::string& s2) {
    return strcasecmp(s1.c_str(), s2.c_str()) < 0;
};
std::map, decltype(comp)> directory(comp);

Code on Ideone

For Window, strcasecmp() does not exist, but you can use _stricmp() instead:

auto comp = [](const std::string& s1, const std::string& s2) {
    return _stricmp(s1.c_str(), s2.c_str()) < 0;
};
std::map, decltype(comp)> directory(comp);

Note: Depending on your system and whether you have to support Unicode or not, you might need to compare strings in a different way. This Q&A gives a good start.