Re: [Mingw-users] undefined reference to `GetComputerNameExA'

[Eli Z. <el...@gn...>]

> Date: Sat, 07 Feb 2015 12:29:32 -0600
> From: Carl Sturtivant <stu...@gm...>
> 
> #include <windows.h>
> #include <stdio.h>
> 
> int main() {
>   char buf[1024];
>   DWORD sz = 1024;
>   //GetComputerNameA( buf, &sz);
>   GetComputerNameExA( 1, buf, &sz);
>   printf( "\"%s\"\n", buf);
> }
> ========
> 
> msys $ gcc -o gethostname gethostname.c
> C:\temp\ccmcT7xy.o:gethostname.c:(.text+0x31):
>   undefined reference to `GetComputerNameExA'
> collect2.exe: error: ld returned 1 exit status

The prototype of GetComputerNameExA is guarded by

  #if (_WIN32_WINNT >= 0x0500)

So you need to

  #define _WIN32_WINNT 0x0500

before including <window.h>.