TCS Coding Practice Question | Factorial of a Number

Given a number, the task is to find the Factorial of this number using Command Line Arguments. Factorial of a non-negative integer is the multiplication of all integers smaller than or equal to n.

Examples:

Input: 3
Output: 6
1 * 2 * 3 = 6

Input: 6
Output: 720
1 * 2 * 3 * 4 * 5 * 6 = 720

Approach:

  • Since the number is entered as Command line Argument, there is no need for a dedicated input line
  • Extract the input number from the command line argument
  • This extracted number will be in String type.
  • Convert this number into integer type and store it in a variable, say num
  • Find the reverse of this number and store in a variable, say rev_num
  • Check if this rev_num and num are same or not.
  • If they are not same, the number is not Palindrome
  • If they are same, the number is a Palindrome

Program:

C

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// C program to find factorial of a number
// using command line arguments
  
#include <stdio.h>
#include <stdlib.h> /* atoi */
  
// Function to find factorial of given number
unsigned int factorial(unsigned int n)
{
    int res = 1, i;
    for (i = 2; i <= n; i++)
        res *= i;
    return res;
}
  
// Driver code
int main(int argc, char* argv[])
{
  
    int num, res = 0;
  
    // Check if the length of args array is 1
    if (argc == 1)
        printf("No command line arguments found.\n");
  
    else {
  
        // Get the command line argument and
        // Convert it from string type to integer type
        // using function "atoi( argument)"
        num = atoi(argv[1]);
  
        // Find the factorial
        printf("%d\n", factorial(num));
    }
    return 0;
}

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Java

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// Java program to find the factorial of a number
// using command line arguments
  
class GFG {
  
    // Method to find factorial of given number
    static int factorial(int n)
    {
        int res = 1, i;
        for (i = 2; i <= n; i++)
            res *= i;
        return res;
    }
  
    // Driver code
    public static void main(String[] args)
    {
  
        // Check if length of args array is
        // greater than 0
        if (args.length > 0) {
  
            // Get the command line argument and
            // Convert it from string type to integer type
            int num = Integer.parseInt(args[0]);
  
            // Get the command line argument
            // and find the factorial
            System.out.println(factorial(num));
        }
        else
            System.out.println("No command line "
                               + "arguments found.");
    }
}

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Output:

  • In C:

  • In Java:



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