Use static variable to compute a running average of numbers entered by the user : static « Language Basics « C++ Tutorial

1. C++ Tutorial
2. Language Basics
3. static

#include <iostream> 
using namespace std; 
 
int f(int i); 
 
int main() 
{ 
  int num; 
 
  do { 
    cout << "Enter numbers (-1 to quit): "; 
    cin >> num; 
    if(num != -1) 
      cout << "average is: " << f(num) << "\n"; 
    
  } while(num > -1); 
 
  return 0; 
} 
 
int f(int i) 
{ 
  static int sum = 0, count = 0; 
 
  sum = sum + i; 
 
  count++; 
 
  return sum / count; 
}

Enter numbers (-1 to quit): 1
average is: 1
Enter numbers (-1 to quit): 2
average is: 1
Enter numbers (-1 to quit): 3
average is: 2
Enter numbers (-1 to quit): 2
average is: 2
Enter numbers (-1 to quit): 1
average is: 1
Enter numbers (-1 to quit): 2
average is: 1
Enter numbers (-1 to quit): 3
average is: 2
Enter numbers (-1 to quit): -1