Factorial of A Number

This code calculates the factorial of a number provided by the user by iterating through a for loop and continuously multiplying the running factorial value by the loop variable i. The result is displayed as number! = factorial.

#include<stdio.h>
main()
{
  int number,factorial=1,i;
  printf("Enter a number: ");
  scanf("%d",&number);
  for(i=1;i<=number;i++)
  {
   factorial=factorial*i;
  }
  printf("%d!=%d\n",number,factorial);
}

Enter a number: 5
5!=120

Explanation:

This C program calculates the factorial of a user-entered number. The factorial of a number is the product of all positive integers from 1 to that number. Here’s a step-by-step explanation of the code:

Header File:

• The program includes the standard C library header <stdio.h> for input and output operations.

Main Function:

• The main function is the entry point of the program.

Variable Declaration:

The following variables are declared:

• number (int): It is used to store the user’s input number for which the factorial will be calculated.
• factorial (int): It is used to store the result of the factorial calculation and is initialized to 1.
• i (int): A loop control variable to iterate from 1 to number.

User Input:

• The program prompts the user to enter a number with the message: “Enter a number for knowing its factorial”.
• The user’s input is read and stored in the number variable using scanf.

Factorial Calculation:

• The program enters a for loop that starts from i = 1 and continues until i is less than or equal to the number.
• Inside the loop, the value of factorial is updated by multiplying it by the current value of i. This operation calculates the factorial of the number.

Result Display:

• After the for loop, the program prints the calculated factorial with the message: “number! = factorial”.

End of Program:

• The program reaches the end of the main function and terminates.