Vowel Counter

#include<iostream>
#include<string>
using namespace std;
void vowelCount(string wordInput, int& aCount, int& eCount, int& iCount, int& oCount, int& uCount);
int main()
{
    cout << "Enter a string for vowel analyzing : ";
    int aCount, eCount, iCount, oCount, uCount;
    string wordInput;
    cin >> wordInput;
    vowelCount(wordInput, aCount, eCount, iCount, oCount, uCount);
    cout << "Number of a's : " << aCount << endl;
    cout << "Number of e's : " << eCount << endl;
    cout << "Number of i's : " << iCount << endl;
    cout << "Number of o's : " << oCount << endl;
    cout << "Number of u's : " << uCount << endl;

    system("read");
    return 0;
}
void vowelCount(string wordInput, int& aCount, int& eCount, int& iCount, int& oCount, int& uCount){
    for(int i = 0; i <= wordInput.length(); i++){
        char temp = wordInput[i];
        switch (temp){
            case 'a':
            case 'A':
                aCount++;
                break;
            case 'e':
            case 'E':
                eCount++;
                break;
            case 'i':
            case 'I':
                iCount++;
                break;
            case 'o':
            case 'O':
                oCount++;
                break;
            case 'u':
            case 'U':
                uCount++;
                break;
        }
    }
}