using std::string with Qt causes run-time error on destruction

Question

Hi.

I have a Qt app that uses another library where the function output is std::string instead of a QString.

So in my program I have a method

void doSomething() {
...
std::string std_string = MyExternalLibraryThatReturnsSTLstring.getString();
QString myQString = QString::fromStdString(std_string);
...
process(myQString);
...
}

When my external lib returns a not-empty std::string everything works fine. But when an empty std::string is returned, the app crashes at the end of the scope. I guessed that has to do with destruction of the std::string object(?).

The conversion to QString works fine, even with an empty std::string.

Can someone tell my why this happens, and how to avoid this run-time error?

(In other threads some people have discussed mixing of debug and release libraries, but I dont think that I have done that. How to find out btw?)

Answer 1

Use "dependency walker" to see on which DLL's your application (and the external DLL, and the QT DLL) are relying.