How do I find out my .exe's entry-point function?

Question

I feel very foolish asking this question, but please bear with me and read the symptoms before commenting "it's `main()`, duh". I'm working on a project in Visual Studio Express 2012. We have hitherto built only for the Win32 (x86) platform but I am converting the .exe build to 64 bit. I now have a fully linked .exe, but a funny thing happened along the way: the entry-point no longer gets called. The entry-point to the (C++, console) program is a C++ function declared at file scope with the following signature: `int main(int argc, char * argv[])`. This function has happily worked in the x86 executable since day 1. It is not being called on x64: - The linker does not complain that it can't find the entry-point. - The loader does not complain that it can't find the entry-point. - When I run the exe from command line, it starts and exits immediately with exit code 127. - gdb, e.g., says "During startup program exited with code 0xc000007b." - There is no output whatsoever on stdout or std…

Accepted Answer

`0xc000007b` is `STATUS_INVALID_IMAGE_FORMAT`. That is, the operating system never even gets the binary loaded far enough to start executing it.

There could be something wrong in your compilation settings. However, usually when I have seen this error, the problem has been in the 64-bit application trying to dynamically link to a 32-bit DLL.

Check your libraries, and verify your paths point to the 64-bit versions of any DLLs.

How do I find out my .exe's entry-point function?

Solution

Problem