每个判断c++都有内置的函数

isalpha
isdigit
isspace
ispunct

#include<iostream>
#include<string>
using namespace std;
int main()
{
    string str;
    while (getline(cin, str))
    {
        int a = 0, b = 0, c = 0, d = 0;
        int len = str.size();
        for (int i = 0; i < len; i++)
        {
            if (isalpha(str[i]))
            {
                a++;
            }
            else if (isspace(str[i]))
            {
                b++;
            }
            else if (isdigit(str[i]))
            {
                c++;
            }
            else if (ispunct(str[i]))
            {
                d++;
            }


        }
        cout << a << endl << b << endl << c << endl << d << endl;

    }




    return 0;
}