VC++ Program for Student details

#include "resource.h"
#include <Windows.h>
WNDCLASSA a;
HINSTANCE h;
long _stdcall dlg(HWND,UINT,UINT,long);
long _stdcall myfunc(HWND,UINT,UINT,long);
long _stdcall dlg1(HWND,UINT,UINT,long);
char name[34];
int rollno;
  int m1,m2,t,avg;
int _stdcall WinMainA(HINSTANCE i,HINSTANCE j,char *k,int l)
{
 HWND h;
 MSG m;
 a.hInstance=i;
 a.lpszClassName="my";
 a.lpfnWndProc=myfunc;
 a.hbrBackground=(HBRUSH)CreateSolidBrush(RGB(255,255,128));
 RegisterClassA(&a);
 h=CreateWindowA("my","STUDENT DETAILS",WS_OVERLAPPEDWINDOW,10,10,200,200,0,0,i,0);
 ShowWindow(h,3);
 while(GetMessage(&m,0,0,0))
  DispatchMessageA(&m);
 return 0;
}
long _stdcall myfunc(HWND w,UINT x,UINT y,long z)
{
 switch(x)
 {
 case WM_LBUTTONDOWN:
  DialogBoxW(h,MAKEINTRESOURCE(DIALOG1),w,(DLGPROC)dlg);
  break;
 case WM_DESTROY:
  PostQuitMessage(0);
  break;
 default:
  return DefWindowProcA (w,x,y,z);
 }
 return 0L;
}
long _stdcall dlg(HWND w1,UINT x1,UINT y1,long z1)
{
 switch(x1)
 {
  
 case WM_COMMAND:
  switch(y1)
  {
   case GET:
    //MessageBoxA(w1,"Show","Student",3);
    name[33]=GetDlgItemTextA(w1,EDIT1,NULL,34);
    rollno=GetDlgItemInt(w1,EDIT2,NULL,true);
    m1=GetDlgItemInt(w1,EDIT3,NULL,true);
    m2=GetDlgItemInt(w1,EDIT4,NULL,true); 
    t=m1+m2;
    avg=t/2;
    break;
   case RESULT:
    SetDlgItemInt(w1,TOTAL,t,true);
    SetDlgItemInt(w1,AVERAGE,avg,true);
    if(avg<35)
    {
     SetDlgItemTextA(w1,RES,"Fail");
     SetDlgItemTextA(w1,GRADE,"D");
    }
    if(avg>=35 && avg<45)
     {
     SetDlgItemTextA(w1,GRADE,"C");
     SetDlgItemTextA(w1,RES,"Pass");
    }
           
    else if(avg>=45 && avg<60)
    {
     SetDlgItemTextA(w1,GRADE,"B");
     SetDlgItemTextA(w1,RES,"Pass");
    }
    else if(avg>=60 && avg<80)
    {
     SetDlgItemTextA(w1,GRADE,"A");
     SetDlgItemTextA(w1,RES,"Pass");
    }
    else if(avg>=80)
    {
     SetDlgItemTextA(w1,GRADE,"DISTINCTION");
     SetDlgItemTextA(w1,RES,"Pass");
    }
    
    break;
   case EXIT:
    exit(0);
  }
  break;
 }
 return 0L;  
}