Factorial of Large Numbers in C++

This C++ Program demonstrates the the computation of Factorial of Large Numbers.

Here is source code of the C++ Program to Find Factorial of Large Numbers. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/* 
```

 * C++ Program to Find Factorial of Large Numbers

```
 */
```
```
#include <cstring>
```
```
#include <iostream>
```
```
#include <cstdlib>
```
```
#define ll long long
```
```
using namespace std;
```
```
 
```
```
int fact[101][200] = {0};
```
```
 
```
```
/* 
```
```
 * Find Factorial of Large Numbers
```

 * fact[i][0] is used to store the number of digits

```
 */
```
```
void fact_large(int n)
```
```
{
```
```
    int i;
```
```
    fact[1][0] = 1;
```
```
    fact[1][1] = 1;
```
```
    if (fact[n][0] == 0) 
```
```
    {
```
```
        for (i = n - 1; i > 0 ; i--) 
```
```
        {
```
```
            if (fact[i][0] != 0)
```
```
                break;
```
```
        }
```
```
        for ( ; i < n; i++) 
```
```
        {
```
```
            int j = 1;
```
```
            int carry = 0;
```
```
            int len = fact[i][0];
```
```
            while (len--)
```
```
            {
```

                int temp = (i + 1) * fact[i][j] + carry;

                fact[i + 1][j] = temp % 10;

```
                carry = temp / 10;
```
```
                j++;
```
```
            }
```
```
            while (carry > 0) 
```
```
            {
```

                fact[i + 1][j] = carry % 10;

```
                carry /= 10;
```
```
                j++;
```
```
            }
```
```
            fact[i + 1][0] = j - 1;
```
```
        }
```
```
    }
```
```
    for (i = fact[n][0]; i > 0; i--) 
```
```
    {
```
```
        cout << fact[n][i];
```
```
    }
```
```
    cout<<endl;
```
```
}
```
```
/* 
```
```
 * Main
```
```
 */
```
```
int main()
```
```
{
```
```
    int n;
```
```
    while (1)
```
```
    {
```

        cout<<"Enter interger to compute factorial(0 to exit): ";

```
        cin>>n;
```
```
        if (n == 0)
```
```
            break;
```
```
        fact_large(n);
```
```
    }
```
```
    return 0;
```
```
}
```

$ g++ fact_large.cpp
$ a.out
 
Enter interger to compute factorial(0 to exit): 100
93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000
Enter interger to compute factorial(0 to exit): 50
30414093201713378043612608166064768844377641568960512000000000000
Enter interger to compute factorial(0 to exit): 72
61234458376886086861524070385274672740778091784697328983823014963978384987221689274204160000000000000000
Enter interger to compute factorial(0 to exit): 0
 
------------------
(program exited with code: 1)
Press return to continue

Sanfoundry Global Education & Learning Series – 1000 C++ Programs.

If you wish to look at all C++ Programming examples, go to C++ Programs.

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