Why does MinGW throw an "undefined reference to WinMain" error when using wWinMain in C ?

Resolving undefined reference to WinMain when using wWinMain in C (MinGW)

When attempting to use wWinMain (HINSTANCE hInstance, HINSTANCE, PWSTR pCmdLine, int nCmdShow) as the program entry point in C under MinGW, an "undefined reference to WinMain" error can occur.

Cause:

MinGW, particularly older versions, does not natively support the wWinMain entry point, which expects a wide-character (WCHAR) command line argument.

Solution:

There are two potential solutions:

1. Use -municode Flag:

Newer versions of MinGW support the -municode linker flag, which switches to an alternate startup code that allows using wWinMain. Add this flag to your command line, linker options in your IDE, or Makefile:

g++ other_options_and_arguments -municode

2. Use WinMain Entry Point:

For older versions of MinGW or if you prefer not to use the -municode flag, you can revert to using the standard WinMain entry point. This requires modifying your code as follows:

• Change wWinMain to WinMain
• Change PWSTR pCmdLine to PSTR pCmdLine

Additional Note:

If you need to access Unicode command line arguments later in your program, use LPWSTR cmd_line = GetCommandLineW(); instead of using the WinMain argument.

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