LINK : fatal error LNK1561: entry point must be defined

**om3ga** · 08-09-2006

I'm trying to compile some code from a book, I have set all the correct linker and compiler options for SDL libs and headers. But I get this error:
LINK : fatal error LNK1561: entry point must be defined

This is my code:

Code:

#include <SDL.h>
int main (int argc, char* argv[]) {
	if (SDL_Init( SDL_INIT_VIDEO ) < 0)
		return -1;
	SDL_WM_SetCaption("Hello World", "Hello World");
	SDL_Surface* screen = SDL_SetVideoMode(640,480, 0, 0);
	SDL_Surface* temp = SDL_LoadBMP("data\\textures\\sdl_logo.bmp");
	SDL_Surface* bg = SDL_DisplayFormat(temp);
	SDL_FreeSurface(temp);
	SDL_Event event;
	bool quit = false;
	while (!quit)
	{
		if (SDL_PollEvent(&event))
		{
			switch (event.type)
			{
			case SDL_QUIT:
				quit = true;
			break;
			case SDL_KEYDOWN:
				switch (event.key.keysym.sym)
				{
				case SDLK_ESCAPE:
					quit = true;
				break;
				}
			break;
			}
		}
		SDL_BlitSurface(bg, NULL, screen, NULL);
		SDL_UpdateRect(screen, 0, 0, 0, 0);
	}
	SDL_FreeSurface (bg);
	SDL_Quit();
	return 0;
}

**FillYourBrain** · 08-09-2006

That's odd. I wonder if something in the SDL header isn't screwing with the main() definition.

**FillYourBrain** · 08-09-2006

what type of project did you set it up as? Did you try a console application?

**om3ga** · 08-09-2006

Tried a console application. I'm using MSVC++ 2005 Express, I tried both Win32 Console App and CLR Console App, but neither worked.

Any other ideas?

-Ben

**Ken Fitlike** · 08-09-2006

msvc 2005 defines UNICODE by default and therefore implicitly uses the wide character variants of main and WinMain (wmain and wWinMain) as entry points. Try disabling unicode and rebuilding.

project menu --> project options --> configuration properties --> General, change character set to 'not set'.

**Viorel** · 08-09-2006

What happens if you comment everything except

Code:

int main (int argc, char* argv[]) 
{
	return 0;
}

What is the value of Entry Point and No Entry Point fields in Project Properties --> Linker --> Advanced panel?

**om3ga** · 08-09-2006

Thanks, but it didn't work, it was already set to "Not set", I tried it on Unicode and Multi-Byte, but neither worked.

-Ben

**om3ga** · 08-09-2006

It's stopped giving me that previous error, and now gives this:
------ Build started: Project: SDLHelloWorld, Configuration: Debug Win32 ------
Compiling...
main.cpp
Linking...
LINK : error LNK2001: unresolved external symbol _main
main.obj : error LNK2019: unresolved external symbol _SDL_Quit referenced in function _SDL_main
main.obj : error LNK2019: unresolved external symbol _SDL_UpdateRect referenced in function _SDL_main
main.obj : error LNK2019: unresolved external symbol _SDL_UpperBlit referenced in function _SDL_main
main.obj : error LNK2019: unresolved external symbol _SDL_PollEvent referenced in function _SDL_main
main.obj : error LNK2019: unresolved external symbol _SDL_FreeSurface referenced in function _SDL_main
main.obj : error LNK2019: unresolved external symbol _SDL_DisplayFormat referenced in function _SDL_main
main.obj : error LNK2019: unresolved external symbol _SDL_LoadBMP_RW referenced in function _SDL_main
main.obj : error LNK2019: unresolved external symbol _SDL_RWFromFile referenced in function _SDL_main
main.obj : error LNK2019: unresolved external symbol _SDL_SetVideoMode referenced in function _SDL_main
main.obj : error LNK2019: unresolved external symbol _SDL_WM_SetCaption referenced in function _SDL_main
main.obj : error LNK2019: unresolved external symbol _SDL_Init referenced in function _SDL_main
C:\Documents and Settings\EVAL\My Documents\Visual Studio 2005\Projects\SDLHelloWorld\Debug\SDLHelloWorld.ex e : fatal error LNK1120: 12 unresolved externals
Build log was saved at "file://c:\Documents and Settings\EVAL\My Documents\Visual Studio 2005\Projects\SDLHelloWorld\SDLHelloWorld\Debug\Bu ildLog.htm"
SDLHelloWorld - 13 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Viorel: I tried that, and it gave the error LINK : error LNK2001: unresolved external symbol _main

The value of entry point was blank, but i changed it to "main", and No Entry Point is No

-Ben

**om3ga** · 08-09-2006

Ok, seems that I hadn't linked SDL.lib and SDLmain.lib properly. Now I get this:

------ Build started: Project: SDLHelloWorld, Configuration: Debug Win32 ------
Linking...
LINK : fatal error LNK1104: cannot open file 'uuid.lib'
Build log was saved at "file://c:\Documents and Settings\EVAL\My Documents\Visual Studio 2005\Projects\SDLHelloWorld\SDLHelloWorld\Debug\Bu ildLog.htm"
SDLHelloWorld - 1 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

I tried setting Ignore Specific Library to "uuid.lib", but that gave this:

------ Build started: Project: SDLHelloWorld, Configuration: Debug Win32 ------
Linking...
MSVCRT.lib(MSVCR80.dll) : error LNK2005: _exit already defined in LIBCMT.lib(crt0dat.obj)
MSVCRT.lib(MSVCR80.dll) : error LNK2005: __isctype already defined in LIBCMT.lib(isctype.obj)
LINK : warning LNK4098: defaultlib 'MSVCRT' conflicts with use of other libs; use /NODEFAULTLIB:library
C:\Documents and Settings\EVAL\My Documents\Visual Studio 2005\Projects\SDLHelloWorld\Debug\SDLHelloWorld.ex e : fatal error LNK1169: one or more multiply defined symbols found
Build log was saved at "file://c:\Documents and Settings\EVAL\My Documents\Visual Studio 2005\Projects\SDLHelloWorld\SDLHelloWorld\Debug\Bu ildLog.htm"
SDLHelloWorld - 3 error(s), 1 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Any ideas?

-Ben

**Mario F.** · 08-09-2006

Well, certainly you wouldn't expect it to work if you set your linker to ignore a library it is asking for...

LINK : fatal error LNK1104: cannot open file 'uuid.lib'

Do you have have the Platform SDK installed?

**om3ga** · 08-09-2006

Ok, got rid of the ignore, added the platform sdk path to the library and include lists, now i get this:
------ Build started: Project: SDLHelloWorld, Configuration: Debug Win32 ------
Linking...
MSVCRT.lib(MSVCR80.dll) : error LNK2005: _exit already defined in LIBCMT.lib(crt0dat.obj)
MSVCRT.lib(MSVCR80.dll) : error LNK2005: __isctype already defined in LIBCMT.lib(isctype.obj)
LINK : warning LNK4098: defaultlib 'MSVCRT' conflicts with use of other libs; use /NODEFAULTLIB:library
C:\Documents and Settings\EVAL\My Documents\Visual Studio 2005\Projects\SDLHelloWorld\Debug\SDLHelloWorld.ex e : fatal error LNK1169: one or more multiply defined symbols found
Build log was saved at "file://c:\Documents and Settings\EVAL\My Documents\Visual Studio 2005\Projects\SDLHelloWorld\SDLHelloWorld\Debug\Bu ildLog.htm"
SDLHelloWorld - 3 error(s), 1 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

-Ben

**Desolation** · 08-09-2006

There you go.

Originally Posted by om3ga

Ok, got rid of the ignore, added the platform sdk path to the library and include lists, now i get this:
------ Build started: Project: SDLHelloWorld, Configuration: Debug Win32 ------
Linking...
MSVCRT.lib(MSVCR80.dll) : error LNK2005: _exit already defined in LIBCMT.lib(crt0dat.obj)
MSVCRT.lib(MSVCR80.dll) : error LNK2005: __isctype already defined in LIBCMT.lib(isctype.obj)
LINK : warning LNK4098: defaultlib 'MSVCRT' conflicts with use of other libs; use /NODEFAULTLIB:library
C:\Documents and Settings\EVAL\My Documents\Visual Studio 2005\Projects\SDLHelloWorld\Debug\SDLHelloWorld.ex e : fatal error LNK1169: one or more multiply defined symbols found
Build log was saved at "file://c:\Documents and Settings\EVAL\My Documents\Visual Studio 2005\Projects\SDLHelloWorld\SDLHelloWorld\Debug\Bu ildLog.htm"
SDLHelloWorld - 3 error(s), 1 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

-Ben

**CornedBee** · 08-09-2006

No, that's a poor solution.

The problem here is that the SDL libs were compiled using a different runtime library setting than your program. Experiment with the runtime library setting in the general options. My best guess is to use multi-threaded static non-debug.

**om3ga** · 08-09-2006

Ok, Multi-threaded DLL works. It gave me an error then about SDL.dll, so I moved SDL.dll to the debug folder inside my project folder, now I get a console window, then this error in a message box with the options "break" and "continue":
Unhandled exception at 0x00401139 in SDLHelloWorld.exe: 0xC0000005: Access violation reading location 0x08c6f99c.

-Ben

**CornedBee** · 08-09-2006

Well, choose break and look at what the debugger tells you.

LINK : fatal error LNK1561: entry point must be defined

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