undefined reference to `WinMain@16' collect2.exe: error: ld returned 1 exit status

Question

I am using eclipse CDT to test the Intel instructions and below is my program:

#define cpuid(func,ax,bx,cx,dx)\
__asm__ __volatile__ ("cpuid":\
 "=a" (ax), "=b" (bx), "=c" (cx), "=d" (dx) : "a" (func));
int Check_CPU_support_AES()
 {
 unsigned int a,b,c,d;
 cpuid(1, a,b,c,d);
 return (c & 0x2000000);
 }

When I compile the above code, I get linkage error as:

Info: Internal Builder is used for build
gcc -O0 -g3 -Wall -c -fmessage-length=0 -o "src\\Intel.o" "..\\src\\Intel.c" 
gcc -o Intel.exe "src\\Intel.o" 
c:/mingw/bin/../lib/gcc/mingw32/4.7.2/../../../libmingw32.a(main.o):main.c:(.text.startup+0xa7): undefined reference to `WinMain@16'
collect2.exe: error: ld returned 1 exit status

Please help me regarding the issue.

Answer 1

Your program isn't complete. You need to implement the OS-expected entry point. In your case, that looks like it's called WinMain.

Answer 2

Yes, Main () function is missing and the compiler is not able to find an entry point for executing the program.

One more reason is even if you have written the main function but if you didnot save the .cpp file and try to compile it will give the same error.So make sure you have successfully saved the .cpp file and then compile and run your code.

Hope this will help since I have faced similar issue and I spent around hours to figure it out , Thanks

Answer 3

1. The main() function is missing.
2. Save as this code as some new file. Again run to compile the code.
3. Check the PATH environment variable.

Answer 4

In VS Code, this can happen when you haven't saved your code. Click Ctrl + s to save the code and then run the program again.

Or to make this happen automatically, go to Settings and search for "save". Scroll down and search for "Whether to save the current file before running" and enable it.

Answer 5

you have to save the file first>> Ctrl + s

Answer 6

Replace main() with main(int argc,char **argv), and it works for me.