Check out example codes for "how use global variables instead of local in c++". It will help you in understanding the concepts better.

Code Example 1

#include<iostream> 
  
using namespace std; 
  
int x;  // Global x 
  
int main() 
{ 
  int x = 10; // Local x 
  cout<<"Value of global x is "<<::x<<endl; 
  cout<<"Value of local x is "<<x;   
  getchar(); 
  return 0; 
}

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