The task is to create a program that can do the maximum factorial possible by the machine using "for" cycle.

I understood i have to use bigger data types (the biggest one is "long long", correct me if i'm wrong), and i also understood the concept of the factorial.

Otherwise, i really do not know how to apply what i know in c .

these is the idea at the base of what i wrote down as of now:

#include <cstdlib>
#include <iostream>
#include <math.h>

include namespace std;

int main(int argc, char *argv[])

{
   long long i, factorial;
   cin<<factorial;

   {
      for(long long i=1; i=factorial; i  )
      {
         factorial=factorial*i
      }
   }

  system("PAUSE");
  return EXIT_SUCCESS;
}

Problems are:

1. I don't know if the code it's wrote correctly
2. by doing "factorial=factorial*i", the "i=factorial" in the "for" cycle doesn't make sense, since it will stop the program before it has to.

This being said, I would like to point out that i am in high school, my programming knowledge is really poor, and for this reason every kind of advice and information is very well accepted :).

Thanks in advance

CodePudding user response：

Maybe you want to compute the maximum factorial that will fit in an unsigned long long data type.

But let us look at the horrible program. I add comments with the problems.

#include <cstdlib> // Not to be used in C  
#include <iostream>
#include <math.h>   // Not needed

include namespace std;   // Completely wrong statement. But even if you would have done it syntactically correct, it should never be used

int main(int argc, char *argv[]) // Neither args nor argv is used
{
   long long i, factorial; // i will be redefine later. factorial is not initialized
   cin<<factorial;  // You want to stream somethin into std::cin?

   {
      for(long long i=1; i=factorial; i  ) // Thats heavy stuff. i=factorial? Nobody know, what will happen
      {
         factorial=factorial*i   // Semicolon missing
      }
   }

  system("PAUSE");  // Do not use in C  
  return EXIT_SUCCESS;   // EXIT_SUCCESS is not defined
}

Maybe the below could give you an idea

#include <iostream>

int main() {
    unsigned long long number{};
    unsigned long long factorial{1};

    std::cin >> number;

    for (unsigned long long i{ 1 }; i <= number;   i)
        factorial = factorial * i;

    std::cout << factorial;
}