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: ";
  }
 }
}