输入一段字符串计算以元音开头的字母有几个

#include <iostream>
#include <string>

int main()
{
using namespace std;

unsigned a =0 ,b = 0,c = 0,d=0;

cout << "输入单词： ";
string tt;
while (cin >> tt && "q" != tt)
{
++a;
char first_char = tt[0];
if (!isalpha(first_char))
{
++b;
}
else if ('a' == first_char || 'A' == first_char ||
'o' == first_char || 'O' == first_char ||
'u' == first_char || 'U' == first_char ||
'e' == first_char || 'E' == first_char ||
'i' == first_char || 'I' == first_char  )
{
++c;
}
else
{
++d;
}
}

cout << "总共输入: " << a << " 个字符串。" << endl;
cout << "元音开头的单词有：" << c << endl;
cout << "不是以字母开头的有：" << b << endl;
cout << "剩余的有：" << d << endl;

cout << endl;

return 0;
}