C Foundation

What is C? C Compiler Installation C Extensions C Compiler C Interpreter C Program Structure

C Basics

C Keywords C Data Types C Identifiers C Variables C Constant C Escape Sequences C Constant and Volatile C Typecast


What is Operator C Comma Operator C Arithmetic Operators C Relational Operators C Logical Operators C Bitwise Operators C Conditional Operators C : : Operator C Operator Priority

Basic IO's

Basic IO's C Formatted Functions C Unformatted Functions C Common Functions

Control Statements

What is Control Statement C if Statement C if else Statement C Nested if Statement C Else if Statement C Break Statement C Continue Statement C Switch Statement C Goto Statement


What is Control Loop C for Loop C Nested for Loop C while Loop C Nested while Loop C do while Loop C Nested do while loop


What is Function C User Defined Functions C Recursion C Passing Parameters


Scope C Local Scope C Global Scope

Storage Classes

What is Storage Class C Auto C Extern C Static C Register


What is Array C One Dimensional Array C Two Dimensional Array C Multi Dimensional Array C Arrays Of Strings


What is String C String Functions


What is Pointer C Pointers Arithmetic C Pointer to Pointer C Pointers and Arrays C Pointers and Strings C Pointer to Functions Void Pointers Null Pointers C Null and Void Pointer


What is Structure C Struct within Struct C Array within Structure C Pointer to Structure C Structure and Function C Enum C Bitfield Structure C Type def


What is Union


What is File C read a file C write a file C File Handling C Error Handling C Low Level Disk I/O C Other file functions

Memory Allocation

What is Memory Allocation C Malloc() C Calloc() C Free() C Realloc() C Coreleft()

C Reference

All ASCII Code Basic C Questions

C Interview

C Interview Sets All Star Patterns All Number Patterns All Alphabet Patterns All Series Patterns
The ones who are crazy enough to think they can change the world are the ones who do.
- Steve Jobs

Factorial Number Using C

Mathematically, factorial of any number means to multiply a series of desecending natural numbers ie) upto 1.

Facts About Factorial Numbers

  • 5! is usually pronounced as "5 factorial" by mathematicians
  • Factorial of 0 is 1 i.e) 0! = 1

Pictorical View

Here is the most impressive structures built by humans in ancient time "The Pyramids".

C factorial number

C Program - Factorial Number

Let us write a c program to find factorial for user entered number

#include <stdio.h>
int main()
int a, i;
printf("Enter a number: ");
for(i = a-1;i > 0;i--)
a *= i;
printf("%d ",a);
return 0;
Enter a number : 5
Factorial of 5 is 120


By closely looking at for-loop will give you a clear idea. Limit for a variable i is set from a-1 to 1 which is multiplied with the product of user entered number for every iteration.

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