C ++阶乘程序做奇怪的数学

Question

Very new to c++. Making this factorial program, and somehow I've scraped through the code and built something, but the value it returns is always 10 times the correct value. For example, factorial for 5 is computed at 1200 instead of 120, and factorial of 3 is computed at 60. Why the extra unit?

This is the code:

#include <iostream>

using namespace std;

int main() {

    int i, j, num;

    cout << "Compute factorial: " << endl;

    cin >> num;

    for (i=1; i<num; i++){

        for (j=num; j>1; j--)

            num *=(j-i);

        cout << num;
    }

    return 0;
}

Answer 1

All you need is one loop. This way should be much simpler.

#include <iostream>

using namespace std;

int main() {

    int i, j=1, num;

    cout << "Compute factorial: " << endl;

    cin >> num;

    for (i=num; i>0; i--){
        j *= i;
    }

    cout << j << endl;
}

Answer 2

for (i=1; i<num; i++){

     num *=i;
}

This should be enough

Answer 3

I think you are not quite clear about for loop,and be careful with the change of num try this piece of code, hope it will help

#include <iostream>

using namespace std;

int main() {

int i, j, num;

cout << "Compute factorial: " << endl;

cin >> num;
int output_num = 1;
for (i=1; i<=num; i++){

        output_num *= i;

}
cout << output_num;

return 0;
}

Answer 4

Use this code :

#include<iostream>
using namespace std;
int main()
{
int num,fact=1;
cout<<" Enter the no. to find its factorial:";
cin>>num;
for(int a=1;a<=num;a++)
{
fact=fact*a;
}
cout<<"Factorial of a given Number is ="<<fact<<endl;
return 0;
}

Output :

Answer 5

using two loops for computing factorial is very complex..... and you do not need it. Try this

#include <iostream>

using namespace std;

int main() {

    int i,num;
    cout << "Compute factorial: " << endl;
    cin >> num;
    for(i=num;i>1;--i)
        num*=(i-1);

        cout << num;

    return 0;
}