Thread: Making it harder than it is?

I'm trying to write a program where the user inputs a sentence, then outputs the number of vowels. But I'm trying to use a function "isVowel" where I first go through the sentence and return true for any vowel, and otherwise false. This is what I have... and I have a feeling I'm making this harder than it needs to be. Help?

Code:

#include <iostream>

using namespace std;

bool isVowel(char);

int main()
{
	int sum;
	char vowel;
	string sentence;
	cout << "Enter a sentence" << endl;
	getline(cin, sentence);
	cout << "There are " << isVowel(sum) << " vowels in this sentence." << endl;

	return 0;
}

bool isVowel(char sum)
{
	sum = sum + true;
	if ("A" || "a" || "E" || "e" || "I" || "i" || "O" || "o" || "U" || "u")
		return true;
	else
		return false;
	
	return sum;
}