# Count the pairs of vowels in the given string

Given a string str consisting of lowercase English alphabets, the task is to count the number of adjacent pairs of vowels.

Examples:

Input: str = “abaebio”
Output: 2
(a, e) and (i, o) are the only valid pairs.

Input: str = “aeoui”
Output: 4

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: Starting from the first character of the string to the second last character, increment count for every character where str[i] as well as str[i + 1] are both vowels. Print the count in the end which is the required count of pairs.

Below is the implementation of the above approach:

## C++

 `// C++ implementation of the approach ` `#include ` `using` `namespace` `std; ` ` `  `// Function that return true ` `// if character ch is a vowel ` `bool` `isVowel(``char` `ch) ` `{ ` `    ``switch` `(ch) { ` `    ``case` `'a'``: ` `    ``case` `'e'``: ` `    ``case` `'i'``: ` `    ``case` `'o'``: ` `    ``case` `'u'``: ` `        ``return` `true``; ` `    ``default``: ` `        ``return` `false``; ` `    ``} ` `} ` ` `  `// Function to return the count of adjacent ` `// vowel pairs in the given string ` `int` `vowelPairs(string s, ``int` `n) ` `{ ` `    ``int` `cnt = 0; ` `    ``for` `(``int` `i = 0; i < n - 1; i++) { ` ` `  `        ``// If current character and the ` `        ``// character after it are both vowels ` `        ``if` `(isVowel(s[i]) && isVowel(s[i + 1])) ` `            ``cnt++; ` `    ``} ` ` `  `    ``return` `cnt; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``string s = ``"abaebio"``; ` `    ``int` `n = s.length(); ` `    ``cout << vowelPairs(s, n); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java implementation of the approach ` `class` `GFG { ` ` `  `    ``// Function that return true ` `    ``// if character ch is a vowel ` `    ``static` `boolean` `isVowel(``char` `ch) ` `    ``{ ` `        ``switch` `(ch) { ` `        ``case` `'a'``: ` `        ``case` `'e'``: ` `        ``case` `'i'``: ` `        ``case` `'o'``: ` `        ``case` `'u'``: ` `            ``return` `true``; ` `        ``default``: ` `            ``return` `false``; ` `        ``} ` `    ``} ` ` `  `    ``// Function to return the count of adjacent ` `    ``// vowel pairs in the given string ` `    ``static` `int` `vowelPairs(String s, ``int` `n) ` `    ``{ ` `        ``int` `cnt = ``0``; ` `        ``for` `(``int` `i = ``0``; i < n - ``1``; i++) { ` ` `  `            ``// If current character and the ` `            ``// character after it are both vowels ` `            ``if` `(isVowel(s.charAt(i)) && isVowel(s.charAt(i + ``1``))) ` `                ``cnt++; ` `        ``} ` ` `  `        ``return` `cnt; ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `main(String args[]) ` `    ``{ ` `        ``String s = ``"abaebio"``; ` `        ``int` `n = s.length(); ` `        ``System.out.print(vowelPairs(s, n)); ` `    ``} ` `} `

## Python3

 `# Python3 implementation of the approach ` ` `  `# Function that return true ` `# if character ch is a vowel ` `def` `isVowel(ch): ` `    ``if` `ch ``in` `[``'a'``, ``'e'``, ``'i'``, ``'o'``, ``'u'``]: ` `        ``return` `True` `    ``else``:  ` `        ``return` `False` ` `  `# Function to return the count of adjacent ` `# vowel pairs in the given string ` `def` `vowelPairs(s, n): ` ` `  `    ``cnt ``=` `0` `    ``for` `i ``in` `range``(n ``-` `1``): ` ` `  `        ``# If current character and the ` `        ``# character after it are both vowels ` `        ``if` `(isVowel(s[i]) ``and` `            ``isVowel(s[i ``+` `1``])): ` `            ``cnt ``+``=` `1` ` `  `    ``return` `cnt ` ` `  `# Driver code ` `s ``=` `"abaebio"` `n ``=` `len``(s) ` `print``(vowelPairs(s, n)) ` ` `  `# This code is contributed ` `# by mohit kumar `

## C#

 `// C# implementation of the approach  ` `using` `System; ` ` `  `class` `GFG  ` `{  ` ` `  `    ``// Function that return true  ` `    ``// if character ch is a vowel  ` `    ``static` `bool` `isVowel(``char` `ch)  ` `    ``{  ` `        ``switch` `(ch)  ` `        ``{  ` `        ``case` `'a'``:  ` `        ``case` `'e'``:  ` `        ``case` `'i'``:  ` `        ``case` `'o'``:  ` `        ``case` `'u'``:  ` `            ``return` `true``;  ` `        ``default``:  ` `            ``return` `false``;  ` `        ``}  ` `    ``}  ` ` `  `    ``// Function to return the count of adjacent  ` `    ``// vowel pairs in the given string  ` `    ``static` `int` `vowelPairs(``string` `s, ``int` `n)  ` `    ``{  ` `        ``int` `cnt = 0;  ` `        ``for` `(``int` `i = 0; i < n - 1; i++)  ` `        ``{  ` ` `  `            ``// If current character and the  ` `            ``// character after it are both vowels  ` `            ``if` `(isVowel(s[i]) && isVowel(s[i + 1]))  ` `                ``cnt++;  ` `        ``}  ` ` `  `        ``return` `cnt;  ` `    ``}  ` ` `  `    ``// Driver code  ` `    ``public` `static` `void` `Main()  ` `    ``{  ` `        ``string` `s = ``"abaebio"``;  ` `        ``int` `n = s.Length;  ` `         `  `        ``Console.WriteLine(vowelPairs(s, n));  ` `    ``}  ` `}  ` ` `  `// This code is contributed by Ryuga  `

## PHP

 ` `

Output:

```2
```

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