Program to count vowels in a string (Iterative and Recursive)

Last Updated : 16 Feb, 2023

Given a string, count the total number of vowels (a, e, i, o, u) in it. There are two methods to count total number of vowels in a string.

Iterative
Recursive

Examples:

Input : abc de
Output : 2

Input : geeksforgeeks portal
Output : 7

1. Iterative Method:

Below is the implementation:

C++

// C++ program to count vowels in a string 
#include<iostream> 
using namespace std; 
  
// Function to check the Vowel 
bool isVowel(char ch) 
{ 
    ch = toupper(ch); 
    return (ch=='A' || ch=='E' || ch=='I' || 
                       ch=='O' || ch=='U'); 
} 
  
// Returns count of vowels in str 
int countVowels(string str) 
{ 
    int count = 0; 
    for (int i=0; i<str.length(); i++) 
        if (isVowel(str[i])) // Check for vowel 
            ++count; 
    return count; 
} 
  
// Main Calling Function 
int main() 
{ 
    //string object 
    string str = "abc de"; 
  
    // Total numbers of Vowel 
    cout << countVowels(str) << endl; 
    return 0; 
} 

Java

// Java program to count vowels in a string 
public class GFG { 
         
    // Function to check the Vowel 
    static boolean isVowel(char ch) 
    { 
        ch = Character.toUpperCase(ch); 
        return (ch=='A' || ch=='E' || ch=='I' || 
                           ch=='O' || ch=='U'); 
    } 
       
    // Returns count of vowels in str 
    static int countVowels(String str) 
    { 
        int count = 0; 
        for (int i = 0; i < str.length(); i++) 
            if (isVowel(str.charAt(i))) // Check for vowel 
                ++count; 
        return count; 
    } 
       
    // Driver code 
    public static void main(String args[]) 
    { 
        //string object 
        String str = "abc de"; 
       
        // Total numbers of Vowel 
        System.out.println(countVowels(str)); 
    } 
} 
// This code is contributed by Sumit Ghosh 

Python3

# Python3 program to count vowels 
# in a string 
  
# Function to check the Vowel 
def isVowel(ch): 
    return ch.upper() in ['A', 'E', 'I', 'O', 'U'] 
  
# Returns count of vowels in str  
def countVowels(str): 
    count = 0
    for i in range(len(str)): 
  
        # Check for vowel 
        if isVowel(str[i]): 
            count += 1
    return count 
  
# Driver Code 
  
# string object  
str = 'abc de'
  
# Total number of Vowels 
print(countVowels(str)) 
  
# This code is contributed  
# by SamyuktaSHegde 

C#

// C# program to count vowels in a string  
using System; 
  
class GFG 
{ 
  
    // Function to check the Vowel  
    public static bool isVowel(char ch) 
    { 
        ch = char.ToUpper(ch); 
        return (ch == 'A' || ch == 'E' ||  
                ch == 'I' || ch == 'O' ||  
                              ch == 'U'); 
    } 
  
    // Returns count of vowels in str  
    public static int countVowels(string str) 
    { 
        int count = 0; 
        for (int i = 0; i < str.Length; i++) 
        { 
              
            // Check for vowel 
            if (isVowel(str[i]))  
            { 
                ++count; 
            } 
        } 
        return count; 
    } 
  
    // Driver code  
    public static void Main(string[] args) 
    { 
          
        //string object  
        string str = "abc de"; 
  
        // Total numbers of Vowel  
        Console.WriteLine(countVowels(str)); 
    } 
} 
  
// This code is contributed by Shrikant13 

PHP

<?php 
// PHP program to count vowels in a string 
  
// Function to check the Vowel 
function isVowel($ch) 
{ 
    $ch = strtoupper($ch); 
    return ($ch =='A' || $ch =='E' ||  
            $ch =='I' || $ch =='O' ||  
            $ch =='U'); 
} 
  
// Returns count of vowels in str 
function countVowels($str) 
{ 
    $count = 0; 
    for ($i = 0; $i < strlen($str); $i++) 
        if (isVowel($str[$i])) // Check for vowel 
            ++$count; 
    return $count; 
} 
  
// Driver Code 
  
//string object 
$str = "abc de"; 
  
// Total numbers of Vowel 
echo countVowels($str) . "\n"; 
  
// This code is contributed 
// by Akanksha Rai 
?> 

Javascript

<script> 
      // JavaScript program to count vowels in a string 
  
      // Function to check the Vowel 
      function isVowel(ch) { 
        ch = ch.toUpperCase(); 
        return ch == "A" || ch == "E" || ch == "I" || ch == "O" || ch == "U"; 
      } 
  
      // Returns count of vowels in str 
      function countVowels(str) 
      { 
        var count = 0; 
        for (var i = 0; i < str.length; i++) 
          if (isVowel(str[i])) 
            
            // Check for vowel 
            ++count; 
        return count; 
      } 
  
      // Main Calling Function 
  
      // string object 
      var str = "abc de"; 
  
      // Total numbers of Vowel 
      document.write(countVowels(str)); 
      document.write("<br>"); 
        
      // This code is contributed by rdtank. 
    </script>

Output

Time Complexity: O(n), where n is the length of the string
Auxiliary Space: O(1)

2. Recursive Method:

Below is the implementation:

C++

// Recursive C++ program to count the total 
// number of vowels using recursion 
#include<iostream> 
using namespace std; 
  
// Function to check the Vowel 
bool isVowel(char ch) 
{ 
    ch = toupper(ch); 
    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 == 1) 
        return isVowel(str[n-1]); 
  
    return countVovels(str, n-1) + isVowel(str[n-1]); 
} 
  
// Main Calling Function 
int main() 
{ 
    // string object 
    string str = "abc de"; 
  
    // Total numbers of Vowel 
    cout << countVovels(str, str.length()) << endl; 
    return 0; 
} 

Java

// Recursive Java program to count the total 
// number of vowels using recursion 
public class GFG { 
         
    // Function to check the Vowel 
    static int isVowel(char ch) 
    { 
        ch = Character.toUpperCase(ch); 
       if(ch=='A' || ch=='E' || ch=='I' || 
            ch=='O' || ch=='U')  
           return 1; 
       else return 0; 
    } 
       
    // to count total number of vowel from 0 to n 
    static int countVowels(String str, int n) 
    { 
        if (n == 1) 
            return isVowel(str.charAt(n - 1)); 
       
        return countVowels(str, n-1) + isVowel(str.charAt(n - 1)); 
    } 
       
    // Main Calling Function 
    public static void main(String args[]) 
    { 
        //string object 
        String str = "abc de"; 
       
        // Total numbers of Vowel 
        System.out.println(countVowels(str,str.length())); 
    } 
} 
// This code is contributed by Sumit Ghosh 

Python 3

# Recursive Python 3 program to count the  
# total number of vowels using recursion 
  
# Function to check the Vowel 
def isVowel(ch): 
    return ch.upper() in ['A', 'E', 'I', 'O', 'U'] 
  
# to count total number of 
# vowel from 0 to n 
def countVovels(str, n): 
    if (n == 1): 
        return isVowel(str[n - 1]); 
  
    return (countVovels(str, n - 1) +
                isVowel(str[n - 1])); 
  
# Driver Code 
  
# string object 
str = "abc de"; 
  
# Total numbers of Vowel 
print(countVovels(str, len(str))) 
  
# This code is contributed  
# by Akanksha Rai 

C#

using System; 
  
// Recursive C# program to count the total  
// number of vowels using recursion  
public class GFG 
{ 
  
    // Function to check the Vowel  
    public static int isVowel(char ch) 
    { 
        ch = char.ToUpper(ch); 
       if (ch == 'A' || ch == 'E' || ch == 'I' || ch == 'O' || ch == 'U') 
       { 
           return 1; 
       } 
       else
       { 
           return 0; 
       } 
    } 
  
    // to count total number of vowel from 0 to n  
    public static int countVowels(string str, int n) 
    { 
        if (n == 1) 
        { 
            return isVowel(str[n - 1]); 
        } 
  
        return countVowels(str, n - 1) + isVowel(str[n - 1]); 
    } 
  
    // Main Calling Function  
    public static void Main(string[] args) 
    { 
        //string object  
        string str = "abc de"; 
  
        // Total numbers of Vowel  
        Console.WriteLine(countVowels(str,str.Length)); 
    } 
} 
  
// This code is contributed by Shrikant13 

PHP

<?php 
// Recursive PHP program to count the total 
// number of vowels using recursion 
  
// Function to check the Vowel 
function isVowel($ch) 
{ 
    $ch = strtoupper($ch); 
    return ($ch == 'A' || $ch == 'E' || 
            $ch == 'I' || $ch == 'O' || 
            $ch == 'U'); 
} 
  
// to count total number of 
// vowel from 0 to n 
function countVovels($str, $n) 
{ 
    if ($n == 1) 
        return isVowel($str[$n - 1]); 
  
    return countVovels($str, $n - 1) + 
               isVowel($str[$n - 1]); 
} 
  
// Driver Code 
  
// string object 
$str = "abc de"; 
  
// Total numbers of Vowel 
echo countVovels($str, strlen($str)) . "\n"; 
  
// This code is contributed  
// by Akanksha Rai 
?> 

Javascript

<script> 
  
// Recursive JavaScript program to count the total 
// number of vowels using recursion 
  
// Function to check the Vowel 
function isVowel(ch) 
{ 
    ch = ch.toUpperCase(); 
    return (ch=='A' || ch=='E' || ch=='I' || 
                        ch=='O' || ch=='U'); 
} 
  
// to count total number of vowel from 0 to n 
function countVovels(str,n) 
{ 
    if (n == 1) 
        return isVowel(str[n-1]); 
  
    return countVovels(str, n-1) + isVowel(str[n-1]); 
} 
  
// Main Calling Function 
  
// string object 
let str = "abc de"; 
  
// Total numbers of Vowel 
document.write(countVovels(str, str.length)); 
  
// This code is contributed by shinjanpatra 
  
</script>

Output

Time Complexity: O(n), where n is the length of the string
Auxiliary Space: O(n), where n is the length of the string since the function is calling itself n times.

How Recursive Code Working.

Find distinct elements common to all rows of a matrix

Prakhar Agrawal

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Program to count vowels in a string (Iterative and Recursive)

C++

Java

Python3

C#

PHP

Javascript

C++

Java

Python 3

C#

PHP

Javascript

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