Print Factorial in C

Table of Content

In C programming, the factorial of a non-negative integer can be calculated using a recursive function or a loop.

What is factorial?

The factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. For example, the factorial of 5 (written as 5!) is equal to 5 x 4 x 3 x 2 x 1 = 120. Factorials are commonly used in combinatorics, probability, and algebra. Factorial of 0 is defined as 1.

Approach to print factorial of a number in C language

The approach to print the factorial of a number in C language can be done using the following steps:

First, include the stdio.h header file in the program, which is necessary for input/output operations.
Define a function called print_factorial that takes in a single integer argument, n.
Initialize a variable result to 1.
Use a for loop to iterate over the integers from 1 to n.
Within the for loop, multiply result by the current value of the loop variable at each iteration.
After the for loop, use the printf function to print the final value of result, along with a message that describes the result.
In the main function, prompt the user to enter a number using the printf function, and read the user’s input using the scanf function.
Pass the user’s input as an argument to the print_factorial function.

Pseudo code to print Factorial of a number

Here is some sample pseudocode for a function that calculates and prints the factorial of a given number in C:

function print_factorial(n) {
    result = 1;
    for (i = 1; i <= n; i++) {
        result = result * i;
    }
    print(result);
}

This function, called print_factorial, takes in a single argument, n, and uses a for loop to iteratively multiply the variable result by the integers from 1 to n. The final value of result is then printed.

C program to print factorial of a number

#include <stdio.h>

int factorial(int n) {
    int result = 1;
    for (int i = 1; i <= n; i++) {
        result *= i;
    }
    return result;
}

int main() {
    int num, fact;
    printf("Enter a number: ");
    scanf("%d", &num);
    fact = factorial(num);
    printf("The factorial of %d is %d\n", num, fact);
    return 0;
}

When this program is run and user inputs number 5, for example, the output will be:

Enter a number: 5
The factorial of 5 is 120

In this program, I have defined a function factorial which takes an integer as input and returns the factorial of the number, this function uses a for loop to iterate over the integers from 1 to n and multiply the result with the current value of the loop variable at each iteration. In the main function, the program prompts the user to enter a number, reads that number using the scanf function, calls the factorial function and assigns the return value to a variable. Finally, the program prints the result using the printf function.