Factorial with recursion

Ever wonder how recursion works in code? Imagine when you are given 6!, you first multiply the next integer factorial in sequence (6! = 6*5!). You repeat the process until 0 is reached. This works the same way in programming. Just think of each multiplication as a small process written as a function. The function gets called until 0 is reached.

#include <iostream>

using namespace std;

int factorial(int i) {
   
   if( i != 0 ) {
       return i*factorial(i-1);
   } else {
       return 1;
   }
};

int main()
{
   for(int i = 0; i <= 6; i++)
       cout << i << "! : " << factorial(i) << endl;

   return 0;
}

#Output
0! : 1                                                                                                                                  
1! : 1                                                                                                                                  
2! : 2                                                                                                                                  
3! : 6                                                                                                                                  
4! : 24                                                                                                                                 
5! : 120                                                                                                                                
6! : 720                                                                                                                                
                                                                                                                                       
                                                                                                                                       
...Program finished with exit code 0