Issue using QString

[rawalinr]

Thanks for this! I thought I was going mad!

I have found the solution to this.

If you downloaded a pre-built version of Qt, and are using VS2010, you will get this problem. Rebuild QT with VS2010 and it fixes it (I tested it).

So, it was toStdString causing the error, because of mismatches between VS2008 and VS2010 code generation for STL/Qt. It was not some other user code before, causing it to manifest there.

I hope you get your problem fixed

Keep well,
David

[d_stranz]

The technical reason is that in VS2008 and VS2010, new applications used the compiler flag "Treat wchar_t as a built in type" with the value "No" ("/Zc:wchar_t-"), whereas the Qt distribution was built with the opposite setting ("/Zc:wchar_t"). The compiler didn't know anything was wrong, nor did the linker. It wasn't until runtime that crashes would occur.

The workaround for VS2010 was to either rebuild the Qt binaries as suggested, or to change the project settings to reverse the flag. Changing the project settings also means that any other external libraries that use wchar_t also have to be built the same way.

In current releases of Visual Studio (and Qt pre-built binaries), the default setting is now "Yes" ("/Zc:wchar_t") everywhere so everything is compatible.