Page 41 - DCAP201_FUNDAMENTALS_OF_DATA_STRUCTURES

Fundamentals of Data Structures

Notes Example: Factorial of 5 = 5 × 4 × 3 × 2 × 1
= 120
1 #include<stdio.h>
2 #include<conio.h>
3
4 int factorial(int);
5
6 int factorial (int i)
7 {
8 int f;
9 if(i==1)
10 return 1;
11 else
12 f = i* factorial (i-1);
13 return f;
14 }
15
16 void main()
17 {
18 int x;
19 clrscr();
20 printf("Enter any number to calculate factorial :");
21 scanf("%d",&x);
22 printf("\nFactorial : %d", factorial (x));
23 getch();
24 }

The output is shown as below:

Source: http://rajkishor09.hubpages.com/hub/C-Programming-Recursive-Function
So from line no. 6 – 14 is a user defined recursive function “factorial” that calculates factorial of
any given number. This function accepts integer type argument/parameter and return integer
value.
In line no. 9 we are checking that whether value of i is equal to 1 or not; i is an integer variable
which contains value passed from main function i.e. value of integer variable x. If user enters 1
then the factorial of 1 will be 1. If user enters any value greater than 1 like 5 then it will execute
statement in line no. 12 to calculate factorial of 5. This line is extremely important because in this
line we implemented recursion logic.

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