Page 43 - DCAP201_FUNDAMENTALS_OF_DATA_STRUCTURES

Fundamentals of Data Structures

Notes value of argument decreases by 1 in each recursive call. When, n becomes equal to 0, the value
of n is returned which is the sum numbers from 5 to 1.
For better visualization of recursion in this example:
sum(5)
=5+sum(4)
=5+4+sum(3)
=5+4+3+sum(2)
=5+4+3+2+sum(1)
=5+4+3+2+1+sum(0)
=5+4+3+2+1+0
=5+4+3+2+1
=5+4+3+3
=5+4+6
=5+10
=15
In this example when, n is equal to 0, there is no recursive call and recursion ends.

Example 3: C program to reverse a sentence using recursion
This program takes a sentence from user and reverses that sentence using recursion. This program
does not use string to reverse the sentence or store the sentence.
Code to reverse a sentence using recursion is given below.
/* Example to reverse a sentence entered by user without using strings.
*/
#include <stdio.h>
void Reverse();
int main()
{
printf(“Enter a sentence: “);
Reverse();
return 0;
}
void Reverse()
{
char c;
scanf(“%c”,&c);
if( c != ‘\n’)
{
Reverse();
printf(“%c”,c);
}
}

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