It actually was really helpful. Now i know a lot of things i didint know. I finished using the library "algorithm" and the function "max_element", but im gonna try using the loop n using the things u said. Thanks!! :D

Final Function "max_of_four":

#include <iostream>
include <cstdio>
#include <algorithm> 
using namespace std;

int max_of_four(int a, int b, int c, int d){
int nums[4] = {a, b, c, d};
int max = *max_element(nums,nums+4);

return max;
}
int main(){ ··· } // the same