Including winmm.lib does not work

I'm trying to code a little program with a simple number guessing game.

I want to play an mp3 file behind it using a simple thread. I have read How to play or open *.mp3 or *.wav sound file in c++ program?, but I can't get it to work. It always spews out the error:

||=== Build: Debug in pinkpantherguessinggame (compiler: GNU GCC Compiler) ===|
C:\Users\Leon\Desktop\pCode\pinkpantherguessinggame\main.cpp|8|warning: ignoring #pragma comment  [-Wunknown-pragmas]|
obj\Debug\main.o||In function `Z11pinkpantherv':|
C:\Users\Leon\Desktop\pCode\pinkpantherguessinggame\main.cpp|16|undefined reference to `_imp__mciSendStringA@16'|
||error: ld returned 1 exit status|
||=== Build failed: 2 error(s), 1 warning(s) (0 minute(s), 1 second(s)) ===|

Here is my code:

#include <cstdlib>
#include <ctime>
#include <iostream>
#include <windows.h>
#include <thread>
#include <Mmsystem.h>

#pragma comment(lib, "Winmm.lib")

using namespace std;

void start(int);

void pinkpanther()
{
    mciSendString("open \"‪E:\\Users\\cdev\\Musik\\pinkpanther.mp\" type mpegvideo alias mp3", NULL, 0, NULL);
    mciSendString("play mp3", NULL, 0, NULL);
}

I tried downloading winmm.lib from somewhere, because it doesn't seem to find the library (just a guess).

Am I doing something wrong, or do I need to include some other header?

Solution

If you read the compiler output carefully, you will see this warning:

warning: ignoring #pragma comment [-Wunknown-pragmas]

That means your compiler (GCC) does not support your code's use of #pragma comment, and so winmm.lib ends up not getting linked into your final executable, thus causing the subsequent linker error:

undefined reference to `_imp__mciSendStringA@16'

This is not a matter of the linker not being able to find winmm.lib, it is a matter of the linker not being told to use winmm.lib in the first place.

#pragma is used to invoke compiler-specific commands. Not all compilers implement #pragma comment. VC++ does (and so do a few others, like BCC32/64), but GCC does not. The other question you linked to was tagged visual-c++, so #pragma comment was appropriate in that case.

In your case, you will have to adjust your build process accordingly to use another way to tell the linker to use winmm.lib. You do that in GCC by using the -l option when invoking the linker, eg -lwinmm.