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++
#include<iostream>
using namespace std;
bool isVowel(char ch)
{
ch = toupper(ch);
return (ch=='A' || ch=='E' || ch=='I' ||
ch=='O' || ch=='U');
}
int countVowels(string str)
{
int count = 0;
for (int i=0; i<str.length(); i++)
if (isVowel(str[i]))
++count;
return count;
}
int main()
{
string str = "abc de";
cout << countVowels(str) << endl;
return 0;
}
|
Java
public class GFG {
static boolean isVowel(char ch)
{
ch = Character.toUpperCase(ch);
return (ch=='A' || ch=='E' || ch=='I' ||
ch=='O' || ch=='U');
}
static int countVowels(String str)
{
int count = 0;
for (int i = 0; i < str.length(); i++)
if (isVowel(str.charAt(i)))
++count;
return count;
}
public static void main(String args[])
{
String str = "abc de";
System.out.println(countVowels(str));
}
}
|
Python3
def isVowel(ch):
return ch.upper() in ['A', 'E', 'I', 'O', 'U']
def countVowels(str):
count = 0
for i in range(len(str)):
if isVowel(str[i]):
count += 1
return count
str = 'abc de'
print(countVowels(str))
|
C#
using System;
class GFG
{
public static bool isVowel(char ch)
{
ch = char.ToUpper(ch);
return (ch == 'A' || ch == 'E' ||
ch == 'I' || ch == 'O' ||
ch == 'U');
}
public static int countVowels(string str)
{
int count = 0;
for (int i = 0; i < str.Length; i++)
{
if (isVowel(str[i]))
{
++count;
}
}
return count;
}
public static void Main(string[] args)
{
string str = "abc de";
Console.WriteLine(countVowels(str));
}
}
|
PHP
<?php
function isVowel($ch)
{
$ch = strtoupper($ch);
return ($ch =='A' || $ch =='E' ||
$ch =='I' || $ch =='O' ||
$ch =='U');
}
function countVowels($str)
{
$count = 0;
for ($i = 0; $i < strlen($str); $i++)
if (isVowel($str[$i]))
++$count;
return $count;
}
$str = "abc de";
echo countVowels($str) . "\n";
?>
|
Javascript
<script>
function isVowel(ch) {
ch = ch.toUpperCase();
return ch == "A" || ch == "E" || ch == "I" || ch == "O" || ch == "U";
}
function countVowels(str)
{
var count = 0;
for (var i = 0; i < str.length; i++)
if (isVowel(str[i]))
++count;
return count;
}
var str = "abc de";
document.write(countVowels(str));
document.write("<br>");
</script>
|
Time Complexity: O(n), where n is the length of the string
Auxiliary Space: O(1)
2. Recursive Method:
Below is the implementation:
C++
#include<iostream>
using namespace std;
bool isVowel(char ch)
{
ch = toupper(ch);
return (ch=='A' || ch=='E' || ch=='I' ||
ch=='O' || ch=='U');
}
int countVovels(string str, int n)
{
if (n == 1)
return isVowel(str[n-1]);
return countVovels(str, n-1) + isVowel(str[n-1]);
}
int main()
{
string str = "abc de";
cout << countVovels(str, str.length()) << endl;
return 0;
}
|
Java
public class GFG {
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;
}
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));
}
public static void main(String args[])
{
String str = "abc de";
System.out.println(countVowels(str,str.length()));
}
}
|
Python 3
def isVowel(ch):
return ch.upper() in ['A', 'E', 'I', 'O', 'U']
def countVovels(str, n):
if (n == 1):
return isVowel(str[n - 1]);
return (countVovels(str, n - 1) +
isVowel(str[n - 1]));
str = "abc de";
print(countVovels(str, len(str)))
|
C#
using System;
public class GFG
{
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;
}
}
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]);
}
public static void Main(string[] args)
{
string str = "abc de";
Console.WriteLine(countVowels(str,str.Length));
}
}
|
PHP
<?php
function isVowel($ch)
{
$ch = strtoupper($ch);
return ($ch == 'A' || $ch == 'E' ||
$ch == 'I' || $ch == 'O' ||
$ch == 'U');
}
function countVovels($str, $n)
{
if ($n == 1)
return isVowel($str[$n - 1]);
return countVovels($str, $n - 1) +
isVowel($str[$n - 1]);
}
$str = "abc de";
echo countVovels($str, strlen($str)) . "\n";
?>
|
Javascript
<script>
function isVowel(ch)
{
ch = ch.toUpperCase();
return (ch=='A' || ch=='E' || ch=='I' ||
ch=='O' || ch=='U');
}
function countVovels(str,n)
{
if (n == 1)
return isVowel(str[n-1]);
return countVovels(str, n-1) + isVowel(str[n-1]);
}
let str = "abc de";
document.write(countVovels(str, str.length));
</script>
|
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.
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