trovaVocali

vector<char> trovaVocali(string str) {
    int strlen = str.length();
    vector<char> chvec;
    int chvec_pointer = 0;
    for (int i=0; i<strlen; i++) {
        string sub = str.substr(i,1);
        if (sub=="a"||sub=="e"||sub=="i"||sub=="o"||sub=="u") {
            chvec.at(chvec_pointer) = sub;
            chvec_pointer++;
        }
        sub = "";
    }
    return chvec;
}