Computing factorial of an integer with recursion and iteration, C++ (vc++)

Computing factorial of an integer with recursion 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;
		}
	}
	else {
		for (num; num >= 1; --num) { // 
			fac *= num;
		}
	}
	return num < 0 ? -1 * fac : 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(num1) << std::endl;
    std::cout << num2<< "! (using iteration) = " << iter_factorial(num1) << std::endl;
    
    // i expected a -120 for -5!. Why don't i have it?
    return 0;

}


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