[c++] Error LNK2019 unresolved external symbol _main referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ)

Error:

Severity Code Description Project File Line Error LNK2019 unresolved external symbol _main referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ) 
Severity    Code    Description Project File    Line
Error   LNK1120 1 unresolved externals  

Code:

#include "windows.h"
#include "tchar.h"
#include "d3d9.h"
#pragma comment(lib, "d3d9.lib")

LPDIRECT3D9 pDirect3D=NULL; 
LPDIRECT3DDEVICE9 pDirect3DDevice=NULL; 
const int segment = 50;
const int NV = segment*13;
struct CUSTOMVERTEX
{
   float x, y, z, rhv;
   
   DWORD color;
};
#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHW|D3DFVF_DIFFUSE)

LPDIRECT3DVERTEXBUFFER9 pVertexBuffer=NULL; 

HRESULT InitialDirect3D(HWND hvnd)
{
   if((pDirect3D=Direct3DCreate9(D3D_SDK_VERSION))==NULL)
      return E_FAIL;
   D3DDISPLAYMODE Display;

   if(FAILED(pDirect3D->GetAdapterDisplayMode(D3DADAPTER_DEFAULT, &Display)))
      return E_FAIL;

   D3DPRESENT_PARAMETERS Direct3DParameter;
   ZeroMemory(&Direct3DParameter, sizeof Direct3DParameter);
 
   Direct3DParameter.Windowed=TRUE;
   Direct3DParameter.SwapEffect=D3DSWAPEFFECT_DISCARD;
   Direct3DParameter.BackBufferFormat=Display.Format;

   if(FAILED(pDirect3D->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hvnd,
                                     D3DCREATE_HARDWARE_VERTEXPROCESSING,
                                     &Direct3DParameter, &pDirect3DDevice)))
      return E_FAIL;
   return S_OK;
}
HRESULT RenderingDirect3D()
{
   if(pDirect3DDevice==NULL)
      return E_FAIL;
   pDirect3DDevice->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(90, 150, 100), 1.f, 0);
   
   pDirect3DDevice->BeginScene();

   pDirect3DDevice->SetStreamSource(0, pVertexBuffer, 0, sizeof(CUSTOMVERTEX));
  
   pDirect3DDevice->SetFVF(D3DFVF_CUSTOMVERTEX);   

    pDirect3DDevice->DrawPrimitive(D3DPT_LINELIST, 0, NV);
    pDirect3DDevice->EndScene();

   pDirect3DDevice->Present(NULL, NULL, NULL, NULL);

   return S_OK;
}

void DeleteDirect3D()
{
   if(pVertexBuffer)
       pVertexBuffer->Release();
   if(pDirect3DDevice)
       pDirect3DDevice->Release();
   if(pDirect3D)
       pDirect3D->Release();
}

HRESULT InitialVertexBuffer()
{
    float u = 0.0;
    int z = 0;
    float points[][2] = {
        {150,150},
        {125,100},
        {150,50},
        {200,50},
        {225,55},
        {285,60},
        {325,25},
        
        {342,30},
        {340,35},
        {340,40},
    
        {325,75},
        {300,125},
        {300,175},
        {305,250},
        {295,287},
        {257,347},
        {200,350},
        {150,325},
        {140,290},

        {142,282},
        {160,280},
        {165,286},
        
        {175,325},
        {215,340},
        {250,335},
        {275,300},
        {275,250},
        {255,200},
        {250,150},
        {275,100},
        {305,65},
        
        {275,85},
        {240,95},
        {215,85},
        {170,65},
        {140,90},
        {160,135},

        {160,150},
        {152.5,150},
        {150,150}
    };
        
    CUSTOMVERTEX Vertexes[NV*2];
    int i = 0;
    while( i < NV*2 )
    {
        u = 0.f;
        for(int j = 0; j < segment; j++)
        {
            Vertexes[i].x = (1-3*u+3*u*u-u*u*u)*points[z][0]+(3*u-6*u*u+3*u*u*u)*points[z+1][0]+(3*u*u-3*u*u*u)*points[z+2][0]+(u*u*u)*points[z+3][0];
            Vertexes[i].y = (1-3*u+3*u*u-u*u*u)*points[z][1]+(3*u-6*u*u+3*u*u*u)*points[z+1][1]+(3*u*u-3*u*u*u)*points[z+2][1]+(u*u*u)*points[z+3][1];
            Vertexes[i].z = 0.5f;
            Vertexes[i].color = 0x00ffffff;
            Vertexes[i].rhv = 1.f;
            u += (float)1/segment;
            i++;
            Vertexes[i].x = (1-3*u+3*u*u-u*u*u)*points[z][0]+(3*u-6*u*u+3*u*u*u)*points[z+1][0]+(3*u*u-3*u*u*u)*points[z+2][0]+(u*u*u)*points[z+3][0];
            Vertexes[i].y = (1-3*u+3*u*u-u*u*u)*points[z][1]+(3*u-6*u*u+3*u*u*u)*points[z+1][1]+(3*u*u-3*u*u*u)*points[z+2][1]+(u*u*u)*points[z+3][1];
            Vertexes[i].z = 0.5f;
            Vertexes[i].color = 0x00ffffff;
            Vertexes[i].rhv = 1.f;
            i++;
        }
        z += 3;
    }
        if(FAILED(pDirect3DDevice->CreateVertexBuffer(NV*2*sizeof(CUSTOMVERTEX), 0, D3DFVF_CUSTOMVERTEX,
        D3DPOOL_DEFAULT, &pVertexBuffer, NULL)))
            return E_FAIL;
   
   void *pVB=NULL;
   if(FAILED(pVertexBuffer->Lock(0, sizeof Vertexes, (void**)&pVB, 0)))
      return E_FAIL;

   memcpy(pVB, Vertexes, sizeof Vertexes);
   
   pVertexBuffer->Unlock();
   
   return S_OK;
}

LRESULT CALLBACK MainWinProc(HWND hwnd, 
                             UINT msg,
                             WPARAM wparam, 
                             LPARAM lparam) 
{
   switch(msg)
   {
      case WM_PAINT:
            RenderingDirect3D();
            ValidateRect(hwnd, NULL);
            break;
      case WM_DESTROY:
            DeleteDirect3D();
            PostQuitMessage(0);
            return 0;
   }
   return DefWindowProc(hwnd, msg, wparam, lparam);
}

int WINAPI WinMain(HINSTANCE hinstance,
                   HINSTANCE hprevinstance,
                   LPSTR lpcmdline, 
                   int ncmdshow) 
{
   WNDCLASSEX windowsclass;
   HWND hwnd; 
   MSG msg; 
   //
   windowsclass.cbSize=sizeof(WNDCLASSEX);
   windowsclass.style=CS_DBLCLKS|CS_OWNDC|CS_HREDRAW|CS_VREDRAW;
   windowsclass.lpfnWndProc=MainWinProc;
   windowsclass.cbClsExtra=0;
   windowsclass.cbWndExtra=0;
   windowsclass.hInstance=hinstance;
   windowsclass.hIcon=LoadIcon(NULL, IDI_APPLICATION);
   windowsclass.hCursor=LoadCursor(NULL, IDC_ARROW);
   windowsclass.hbrBackground=(HBRUSH)GetStockObject(GRAY_BRUSH);
   windowsclass.lpszMenuName=NULL;
   windowsclass.lpszClassName=_T("WINDOWSCLASS");
   windowsclass.hIconSm=LoadIcon(NULL, IDI_APPLICATION);
   
   if(!RegisterClassEx(&windowsclass))
      return 0;
   
   if(!(hwnd=CreateWindowEx(
      NULL,
      _T("WINDOWSCLASS"), 
      _T("Desenam litera G"), 
      WS_OVERLAPPEDWINDOW|WS_VISIBLE, 
      CW_USEDEFAULT, 0, 
      CW_USEDEFAULT, 0, 
      NULL, 
      NULL, 
      hinstance, 
      NULL))) 
      return 0;

   if(SUCCEEDED(InitialDirect3D(hwnd)))
   {
      if(SUCCEEDED(InitialVertexBuffer()))
      {
         ShowWindow(hwnd, SW_SHOWDEFAULT); 
         UpdateWindow(hwnd); 
         ZeroMemory(&msg, sizeof msg);
         while(msg.message!=WM_QUIT)
         {
            if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
            {
               TranslateMessage(&msg);
               DispatchMessage(&msg);
            }
            else
               RenderingDirect3D();
         }
      }
   }

   return msg.wParam;
}

Old thread but for me it started working (after following all advise above) when i renamed int main(void) to int wmain(void) and removed WIN23 from cmake's add_executable().

This is an edge case, but you can also get this error if you are building an MFC application with CMake.

In that case, you need to add the following definitions:

ADD_DEFINITIONS(-D_AFXDLL) SET(CMAKE_MFC_FLAG 2) # or 1 if you are looking for the static library

If you are compiling with unicode, the following properties also need to be added:

set_target_properties(MyApp PROPERTIES COMPILE_DEFINITIONS _AFXDLL,_UNICODE,UNICODE,_BIND_TO_CURRENT_CRT_VERSION,_BIND_TO_CURRENT_MFC_VERSION LINK_FLAGS "/ENTRY:\"wWinMainCRTStartup\"" )

Soure: FAQ: How to use MFC with CMake

This worked for me:

(I don't have enough rep to embed pictures yet -- sorry about this.)

I went into Project --> Properties --> Linker --> System.

IMG: Located here, as of Dec 2019 Visual Studio for Windows

My platform was set to Active(Win32) with the Subsystem as "Windows". I was making a console app, so I set it to "Console".

IMG: Changing "Windows" --> "Console"

Then, I switched my platform to "x64".

IMG: Switched my platform from Active(32) to x64

I faced the same problem too and I found out that I selected "new Win32 application" instead of "new Win32 console application". Problem solved when I switched. Hope this can help you.

Similar to @??? I had the wrong application type configured for a dll. I guess that the project type changed due to some bad copy pasting, as @Daniel Struhl suggested.

How to verify: Right click on the project -> properties -> Configuration Properties -> General -> Project Defaults -> Configuration Type.

Check if this field contains the correct type, e.g. "Dynamic Library (.dll)" in case the project is a dll.

I deleted the file with main() function in my project when I wanted to change project type to static library.

I Forgot to change Properties -> General -> Configuration Type

from

Application(.exe)

to

Static Library (.lib)

This too gave me the same error.

Check project configuration. Linker->System->SubSystem should be Windows.

The problem might originate from a macro instruction in SDL_main.h

In that macro your main(){} is renamed to SDL_main(){} because SDL needs its own main(){} on some of the many platforms they support, so they change yours. Mostly it achieves their goal, but on my platform it created problems, rather than solved them. I added a 2nd line in SDL_main.h, and for me all problems were gone.

#define main SDL_main    //Original line. Renames main(){} to SDL_main(){}. 

#define main main        //Added line. Undo the renaming.

If you don't like the compiler warning caused by this pair of lines, comment both lines out.

If your code is in WinApp(){} you don't have this problem at all. This answer only might help if your main code is in main(){} and your platform is similar to mine.

I have: Visual Studio 2019, Windows 10, x64, writing a 32 bit console app that opens windows using SDL2.0 as part of a tutorial.

just add:

int main()
{
    //you can leave it empty
    return 0;
}

to your project and everything will work its causes because of visual studio try to find the main function to start the project and didn't found it

I had same Problem when i was trying to create executable from program that having no main() method. When i included sample main() method like this

int main(){
  return 0;
}

It solved

Solution for me is: I clean both the solution and the project. And just rebuild the project. This error happens because I tried to delete the main file (only keep library files) in the previous build so at the current build the old stuff is still kept in the built directory. That's why unresolved things happened. "unresolved external symbol _main referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ) "

If it is a windows system, then it may be because you are using 32 bit winpcap library in a 64 bit pc or vie versa. If it is a 64 bit pc then copy the winpcap library and header packet.lib and wpcap.lib from winpcap/lib/x64 to the winpcap/lib directory and overwrite the existing

I got the same error because I created a new object from a templated class using the template name without specifying the type explicitly like this:

int main()
{

    MyClass<T> Test2(5.60, 6.6); <- This is wrong
           ^^^
    return 0;
}

The correct way to do it was to specify exactly what T was like this:

int main()
{

    MyClass<double> Test2(5.60, 6.6); <- This is right
            ^^^^^^
    return 0;
}

Select the project. Properties->Configuration Properties->Linker->System.

My problem solved by setting below option. Under System: SubSystem = Console(/SUBSYSTEM:CONSOLE)

Or you can choose the last option as "inherite from the parent".

Right click on project. Properties->Configuration Properties->General->Linker.

I found two options needed to be set. Under System: SubSystem = Windows (/SUBSYSTEM:WINDOWS) Under Advanced: EntryPoint = main

I had to #include <tchar.h> in my windows service application. I left it as a windows console type subsystem. The "Character Set" was set to UNICODE.

If you use CMake you have to set WIN32 flag in add_executable

add_executable(${name} WIN32 ${source_files})

See CMake Doc for more information.