Chapter 3, Problem 21C

Explanation of Solution

Program code:

// Recursive C++ program to count the total

// number of vowels using recursion

#include<cstdlib>

#include<iostream>

using namespace std;

// Function to check the Vowel

bool isVowel(char ch)

{

// make the letter upper case

ch = toupper(ch);

// check the vowels

return (ch=='A' || ch=='E' || ch=='I' ||

ch=='O' || ch=='U');

}

// to count total number of vowel from 0 to n

int countVovels(string str, int n)

{

//if n is equal to 1

if (n == 1)

//return the value

return isVowel(str[n-1]);

//call the function countVovels

return countVovels(str, n-1) + isVowel(str[n-1]);

}

// Main Calling Function

int main()

{

// string object

string str = "abcde";

//get the length of the string

int len;

len=str.size();

//call the method countVovels()

int v=countVovels(str, str.length());

int c;

// Total numbers of Vowel

cout << "no of vowels"<<countVovels(str, str...