Computing the factorial of an integer using factorial and iteration, C++ (vc++)

Computing the factorial of an integer using factorial and iteration

//Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23506 for x86

#include <iostream>
long long rec_factorial(int num)
{
    if (num == 0 || num == 1) {
        return 1;
    }
    else if (num < 0) {
        num = abs(num);  // could still be written as num *=-1;
        return -1*(num*rec_factorial(num - 1));
    }
    else {
        return num*rec_factorial(num - 1);
    }
}

// factorial without using recursion
long long iter_factorial(int num)
{
    long long fac{ 1};
    if (num == 0 || num == 1) {
        return 1;
    }
    else if (num < 0) {
        num = abs(num);
        for (int i = 1; i <= num; i++) {
            fac *= i;
        }
        return -1*fac;
    }
    else {
        for (num; num >= 1; --num) { // 
            fac *= num;
        }
        return fac;
    }
}
int main()
{
    int num1{5};
    int num2{-5};
    
    std::cout << num1<< "! (using recursion) = " << rec_factorial(num1) << std::endl;
    std::cout << num1<< "! (using iteration) = " << iter_factorial(num1) << std::endl;
    std::cout << num2<< "! (using recursion) = " << rec_factorial(num2) << std::endl;
    std::cout << num2<< "! (using iteration) = " << iter_factorial(num2) << std::endl;
    
   return 0;
}


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