CodeRunBox
Compiler
Glossary
Example
Course
Python
JavaScript
C
C++
Java
R
Kotlin
Introduction
C "Hello, World!" ProgramPrint an Integer (Entered by the User)Add Two IntegersMultiply Two Floating-Point NumbersFind ASCII Value of a CharacterCompute Quotient and RemainderFind the Size of int, float, double and charSwap Two Numbers
Decision Making and Loops
Check Whether a Number is Even or OddCheck Whether a Character is a Vowel or ConsonantFind the Largest Number Among Three NumbersFind the Roots of a Quadratic EquationCheck Leap YearCheck Whether a Number is Positive or NegativeCheck Whether a Character is an Alphabet or notCalculate the Sum of Natural NumbersFind Factorial of a NumberGenerate Multiplication TableDisplay Fibonacci SequenceFind GCD of two NumbersFind LCM of two NumbersDisplay Characters from A to Z Using LoopCount Number of Digits in an IntegerReverse a NumberCalculate the Power of a NumberCheck Whether a Number is Palindrome or NotCheck Whether a Number is Prime or NotDisplay Prime Numbers Between Two IntervalsCheck Armstrong NumberDisplay Armstrong Number Between Two IntervalsDisplay Factors of a NumberMake a Simple Calculator Using switch...casePrint Pyramids and Patterns
Functions
Demonstrate the Working of Keyword longDisplay Prime Numbers Between Intervals Using FunctionCheck Prime or Armstrong Number Using User-defined FunctionCheck Whether a Number can be Expressed as Sum of Two Prime NumbersFind the Sum of Natural Numbers using RecursionFind Factorial of a Number Using RecursionFind G.C.D Using RecursionConvert Binary Number to Decimal and vice-versaConvert Octal Number to Decimal and vice-versaConvert Binary Number to Octal and vice-versaReverse a Sentence Using Recursioncalculate the power using recursion
Arrays and Pointers
Calculate Average Using ArraysFind Largest Element in an ArrayCalculate Standard DeviationAdd Two Matrices Using Multi-dimensional ArraysMultiply Two Matrices Using Multi-dimensional ArraysFind Transpose of a MatrixMultiply two Matrices by Passing Matrix to a FunctionAccess Array Elements Using PointerC Program Swap Numbers in Cyclic Order Using Call by ReferenceFind Largest Number Using Dynamic Memory Allocation
Strings
Find the Frequency of Characters in a StringCount the Number of Vowels, Consonants and so onRemove all Characters in a String Except AlphabetsFind the Length of a StringConcatenate Two StringsCopy String Without Using strcpy()Sort Elements in Lexicographical Order (Dictionary Order)
Structures and Unions
Store Information of a Student Using StructureAdd Two Distances (in inch-feet system) using StructuresAdd Two Complex Numbers by Passing Structure to a FunctionCalculate Difference Between Two Time PeriodsStore Information of Students Using StructureStore Data in Structures Dynamically
File I/O
Write a Sentence to a FileRead the First Line From a FileDisplay its own Source Code as Output

C Program to Find Factorial of a Number

To understand this example, you should have the knowledge of the following C programming topics:

The factorial of a positive number n is given by:


              
factorial of n (n!) = 1 * 2 * 3 * 4....n

The factorial of a negative number doesn’t exist. And, the factorial of 0 is 1.

Factorial of a Number


              
#include <stdio.h>
int main() {
    int n, i;
    unsigned long long fact = 1;
    printf("Enter an integer: ");
    scanf("%d", &n);

    // shows error if the user enters a negative integer
    if (n < 0)
        printf("Error! Factorial of a negative number doesn't exist.");
    else {
        for (i = 1; i <= n; ++i) {
            fact *= i;
        }
        printf("Factorial of %d = %llu", n, fact);
    }

    return 0;
}

Output


              
Enter an integer: 10
Factorial of 10 = 3628800

This program takes a positive integer from the user and computes the factorial using for loop.

Since the factorial of a number may be very large, the type of factorial variable is declared as unsigned long long.

If the user enters a negative number, the program displays a custom error message.

You can also find the factorial of a number using recursion.