Open Class Library FAQ v0.1e

Error LNK2029

The error LNK2029 is caused by the linker when you have OCL calls in your source, but you didn't compile with the /Gm+ parameter. The error may look as follows:

CPPOOC3.LIB (iexcept.cpp) : error LNK2029: "_errno" : unresolved external Charlie Choc (cchoc@mindspring.com) says: Make sure you are compiling with the Gm+ option, the Open Class Library requires the multi-threaded otpion. In a multi-thread environment _errno is a function, in a single thread environment it is an int.

Another situation that will cause a LNK2029 error is when a method for a class has been declared, but not defined in any of the source files. For example, the linker will generate the following error: test.obj(test.cpp) : error LNK2029: "{MyWindow}IVBase::virtual-fn-table-ptr" : unresolved external if the following source file is compiled & linked:

(note that while the constructor has been declared and defined, the destructor was declared but accidently left out undefined)

#include <iframe.hpp> class mywindow : public IFrameWindow { public: MyWindow(); ~MyWindow(); }; MyWindow::MyWindow() : IFrameWindow() { return; } int main() { return 0; }

Note:: See also Required Compiler Flag and How to Link