what median_unsafe in C++ mean

I run into a C++ code:

    vector<double> PITs;
    if(PITs.size() > 0) PIT 开发者_开发技巧= util::median_unsafe(PITs);

What is mean by util::median_unsafe, why I cant find it in C++ reference? thanks

Maybe because it is not a part of C++ standard library. It is probably something from another part of the code you have. If you use some IDE it probably supports something like "GoTo Declaration/Definition", so you might be able to find out where that function comes from.