[c++] LINK : fatal error LNK1561: entry point must be defined ERROR IN VC++

I installed MS VS VC++ for the first time in order to start programming OpenGL with GLFW library. I follower instructions on how to install it over at http://shawndeprey.blogspot.com/2012/02/setting-up-glfw-in-visual-studio-2010.html Then I wrote this simple program, just to test it, which did work on Eclipse:

#include <stdlib.h>
#include <GL/glfw.h>

using namespace std;

int main()
{
    int running = GL_TRUE;
    if (!glfwInit()) {
        exit(EXIT_FAILURE);
    }

    if (!glfwOpenWindow(300, 300, 0, 0, 0, 0, 0, 0, GLFW_WINDOW)) {
        glfwTerminate();
        exit(EXIT_FAILURE);
    }

    while (running) {
        // glClear( GL_COLOR_BUFFER_BIT );
        glfwSwapBuffers();
        running = !glfwGetKey(GLFW_KEY_ESC) && glfwGetWindowParam(GLFW_OPENED);
    }

    glfwTerminate();
    exit(EXIT_SUCCESS);
    return 0;
}

But then I got this awful error:

------ Build started: Project: first1, Configuration: Debug Win32 ------
   LINK : fatal error LNK1561: entry point must be defined
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

I know, I've looked around on the internet and the only solution I found was "It requires main() function in order to work". I obviously have it, right there, but it still throws me the same fatal error :(

Would be great to get response on how to fix it. There might me a flaw in the installation process or something.

In my case, the program was running fine, but after one day, I just ran into this problem without doing anything...

The solution was to manually add 'Main' as the Entry Point (before editing, the area was empty):

You can get this error if you define a project as an .exe but intent to create a .lib or a .dll

change it to Console (/SUBSYSTEM:CONSOLE) it will work

In Visual Studio: Properties -> Advanced -> Entry Point -> write just the name of the function you want the program to begin running from, case sensitive, without any brackets and command line arguments.

Main was missing in the entry point configuration.

It cant find the entry point for your program, in this case main(). Your linker settings are likely incorrect.

See this post here

I've had this happen on VS after I changed the file's line endings. Changing them back to Windows CR LF fixed the issue.

Is this a console program project or a Windows project? I'm asking because for a Win32 and similar project, the entry point is WinMain().

1. Right-click the Project (not the Solution) on the left side.
2. Then click Properties -> Configuration Properties -> Linker -> System

If it says Subsystem Windows your entry point should be WinMain(), i.e.

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nShowCmd)
{
   your code here ...
}

Besides, speaking of the comments. This is a compile (or more precisely a Link) error, not a run-time error. When you start to debug, the compiler needs to make a complete program (not just to compile your module) and that is when the error occurs.

It does not even get to the point being loaded and run.