Q. Write a program to find factorial of a given number.



Factorial :- The factorial of a number is the product of all the integers from 1 to that number.

For Example :- Factorial of 5 = 120 (5*4*3*2*1).

Factorial Algorithm

START
step 1 : Read the number n
step 2 : [Initialize]
        i=1, fact=1
step 3 : Repeat step 4 through 6 until i=n
step 4 : fact=fact*i
step 5 : i=i+1
step 6 : Print fact
STOP


Factorial Program

  • C
  • C++
  • Java
  • Python
  • C#
  • PHP
  • #include <stdio.h>
    int main() {
        int num=7, i;
        unsigned long long fact = 1;
        
        if (num < 0)
            printf("Error! Factorial of a negative number doesn't exist.");
        else {
            for (i = 1; i <= num; ++i) {
                fact *= i;
            }
            printf("Factorial of %d = %llu", num, fact);
        }
    
        return 0;
    }
    
    #include <iostream>
    using namespace std;
    
    int main()
    {
        unsigned int num=7;
        unsigned long long factorial = 1;
    
    
        for(int i = 1; i <=num; ++i)
        {
            factorial *= i;
        }
    
        cout << "Factorial of " << num << " = " << factorial;    
        return 0;
    }
    
    public class LFC {
    
        public static void main(String[] args) {
    
            int num = 7;
            long factorial = 1;
            for(int i = 1; i <= num; ++i)
            {
                // factorial = factorial * i;
                factorial *= i;
            }
            System.out.printf("Factorial of %d = %d", num, factorial);
        }
    }
    
    
    num = 7
    
    # To take input from the user
    #num = int(input("Enter a number: "))
    
    factorial = 1
    
    # check if the number is negative, positive or zero
    if num < 0:
       print("Error, factorial does not exist for negative numbers")
    elif num == 0:
       print("The factorial of 0 is 1")
    else:
       for i in range(1,num + 1):
           factorial = factorial*i
       print("Factorial of",num,"=",factorial)
    
    using System;  
      public class LFC  
       {  
         public static void Main(string[] args)  
          {  
           int i,fact=1,num=7;      
              
           for(i=1;i<=num;i++){      
            fact=fact*i;      
           }      
           Console.Write("Factorial of " +num+" = "+fact);    
         }  
      }  
    
    
    $num = 7;  
    $fact = 1;  
    for ($x=$num; $x>=1; $x--)   
    {  
      $fact = $fact * $x;  
    }  
    echo "Factorial of $num = $fact";  
      
    
    #include <stdio.h>
    int main() {
        int num=7, i;
        unsigned long long fact = 1;
        
        if (num < 0)
            printf("Error! Factorial of a negative number doesn't exist.");
        else {
            for (i = 1; i <= num; ++i) {
                fact *= i;
            }
            printf("Factorial of %d = %llu", num, fact);
        }
    
        return 0;
    }
    

    Output

    Factorial of 7 = 5040
    

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