Use function in an expression : Expression « Language Basics « C++ Tutorial

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

#include <iostream>  
using namespace std;  
  
double box(double length, double width, double height); // use double data  
  
int main()  
{  
  double sum;  
  
  sum = box(10.1, 11.2, 3.3) + box(5.5, 6.6, 7.7) + box(4.0, 5.0, 8.0);  
  
  cout << "The sum of the volumes is " <<  sum << "\n";  
  cout << "The average volume is " << sum / 3.0 << "\n";  
  
  return 0;  
}  
  
// This version of box uses double data.  
double box(double length, double width, double height)  
{  
  return length * width * height ;  
}

The sum of the volumes is 812.806
The average volume is 270.935