What is 'CPoint' : ambiguous symbol atltypes.h?

It was a dark and rainy night.. I was trying to do something useful.. what I don't remember right now.. But I was getting this weird problem...

Error 1 error C2872: 'CPoint' : ambiguous symbol atltypes.h
Error 2 error C2872: 'CRect' : ambiguous symbol atltypes.h
Error 3 error C2872: 'CSize' : ambiguous symbol atltypes.h
.
.
Error N error C2872: 'CReality' : ambiguous symbol life.h

Obviously (is it?) I was using ATL and WTL to do something... After scratching my head, googling and going through few WTL headers .. I found the solution. Just include the following, just after you add the #include <windows.h> :

#include <atlbase.h>

#if (_ATL_VER >= 0x0700)
#include <atlstr.h>
#include <atltypes.h>
#endif

#if (_ATL_VER >= 0x0700)
#define _WTL_NO_CSTRING
#define _WTL_NO_WTYPES
#define _WTL_NO_UNION_CLASSES
#endif

#include <atlapp.h>

WTL::CRichEditCtrl

WTL::CRichEditCtrl needs the following line for initialization, add it in your DllMain or _tWinMain and it resolves the issue:

HINSTANCE hInstRich = ::LoadLibrary(CRichEditCtrl::GetLibraryName());

Unfortunately I forgot that Rich Edit isn’t a common control and is not initialized with InitCommonControlsEx.

Some COM Books

Some books on COM. I just keep forgetting the name !!

1. Inside OLE, 2nd Edition, by Kraig Brockschmidt (Microsoft Press)
2. Understanding ActiveX and OLE, by David Chappell (Microsoft Press)
3. Inside COM, by Dale Rogerson (Microsoft Press)

Print map of India using C

I don't know from where I got this code but its amazing ;)

#include <stdio.h> 
int main()
{
 int a,b,c;
 int count = 1;
 for (b=c=10;a="- FIGURE?, UMKC,XYZHello Folks,\
      TFy!QJu ROo TNn(ROo)SLq SLq ULo+\
      UHs UJq TNn*RPn/QPbEWS_JSWQAIJO^\
      NBELPeHBFHT}TnALVlBLOFAkHFOuFETp\
      HCStHAUFAgcEAelclcn^r^r\\tZvYxXy\
      T|S~Pn SPm SOn TNn ULo0ULo#ULo-W\
      Hq!WFs XDt!" [b+++21]; )

      for(; a-- > 64 ; )
       putchar ( ++c=='Z' ? c = c/ 9:33^b&1); return 0; 

 return 0;
}

The Output

                    !!!!!!                                                     
                    !!!!!!!!!!                                                 
                     !!!!!!!!!!!!!!!                                           
                       !!!!!!!!!!!!!!                                          
                     !!!!!!!!!!!!!!!                                           
                      !!!!!!!!!!!!                                             
                      !!!!!!!!!!!!                                             
                        !!!!!!!!!!!!                                           
                        !!!!!!!!                                               
                        !!!!!!!!!!                                             
                       !!!!!!!!!!!!!!                                          
                     !!!!!!!!!!!!!!!!                                          
                    !!!!!!!!!!!!!!!!                                  !!!!!    
                  !!!!!!!!!!!!!!!!!!!                               !!!!!!!!!! 
                 !!!!!!!!!!!!!!!!!!!!!!!                 !         !!!!!!!!!!  
            !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!              !!     !!!!!!!!!!!!    
           !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!        !!      !!!!!!!!       
            !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!      
             !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!       
              !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!  !!!!!!!!!!!!       
       !!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!        !!!!!!        
      !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!      !!!!!         
          !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!        !!!          
        !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!        !          
          !!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                       
           !!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                         
                  !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                          
                 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                           
                  !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                               
                  !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!                               
                  !!!!!!!!!!!!!!!!!!!!!!!!!!!!                                 
                  !!!!!!!!!!!!!!!!!!!!!!!!!!                                   
                  !!!!!!!!!!!!!!!!!!!!!!!!!                                    
                   !!!!!!!!!!!!!!!!!!!!!!!!                                    
                    !!!!!!!!!!!!!!!!!!!!                                       
                    !!!!!!!!!!!!!!!!!!!                                        
                     !!!!!!!!!!!!!!!!                                          
                      !!!!!!!!!!!!!!!!                                         
                      !!!!!!!!!!!!!!!                                          
                       !!!!!!!!!!!!!!                                          
                        !!!!!!!!!!!!                                           
                        !!!!!!!!!!!!                                           
                        !!!!!!!!!!!!                                           
                          !!!!!!!!                                             
                          !!!!!!                                               
                           !!!!                                                
   

Query system for an environment variable value using C/C++

Today one of my colleague asked me how to query an environment variable using C++. The solution is simple, just use getenv() method. See the below code.

#include <iostream>
#include <cstdlib>
#include <string>

using namespace std;
#pragma warning(disable: 4996) // disable warning for getenv()

int main()
{
 char *pointer = NULL;

 string str;
 cout<<"Enter the environment variable: ";

 while (cin>>str) {
  if(str.compare("exit") == 0) break;
  if(pointer = getenv(str.c_str())) {
   cout<<endl<<"Value of \""<<str<<"\" Variable: "<<pointer<<endl<<endl<<"Enter the environment variable: ";
  }else {
   cout<<"No such variables defined."<<endl<<"Enter the environment variable: ";
  }
 }
}