Program 312: Factorial of a number using Recursion

Program 312: Factorial of a number using Recursion
 

#include<stdio.h>
int GetFactorial(int number);
 main()
 {
  int number,factorial;
  printf("Enter a number for knowing it's factorial\n");
  scanf("%d",&number);
  factorial=GetFactorial(number);
  printf("%d!=%d\n",number,factorial);
 }

int GetFactorial(int number)
{
 if(number>0)
 {
  return number*GetFactorial(number-1);
 }
 else
 {
  return 1;
 }
}

Explanation:

1. This program starts with initializing :
   • number → To store given number to get Factorial
   • factorial →Used to store output
   • int GetFactorial→ Declaration of function

2.  printf("Enter a number for knowing it's factorial\n");
     scanf("%d",&number);

   To take input from user

3. factorial=GetFactorial(number);

   Calling GetFactorail Function and received output from the called function(i.e GetFactorial) will be sored in factorial

4. int GetFactorial(int number)
   {
    if(number>0)
    {
     return number*GetFactorial(number-1);
    }
    else
    {
     return 1;
    }
   }

   Now lets take a number 4 to get factoraial of 4.
   now number is greater than 0(i.e 4>0) is true so if part is executed
5. Now
   
   1. return 4*GetFactorial(4-1);
   2. GetFactorial(3)---> return 3*GetFactorial(3-1)
   3. Substitute 3*GetFactorial(3-1) in Step 1
   4. So Step 1 will be return 4*3*GetFactorial(3-1)
   5. Now again GetFactorial(2)--->return 2*GetFactorial(2-1)
   6. So Step 4 will be return 4*3*2*GetFactorial(2-1)
   7. GetFactorial(1)--->return 1*GetFactorial(1-1)
   8. So again Step 6 will be return 4*3*2*1*GetFactorial(1-1)
   9. As GetFactorial(0)-->Since if(0>0) is false else part  will be executed.So it will return 1.
   10. So Step 8  will be return 4*3*2*1*1
   11. Finally it returns value of 4*3*2*1*1=24
6. factorial=24 and this will be printed as output

Output: