题解 | 统计字符

#include <iostream>
#include <cctype>
using namespace std;

int main() {
    string str;
    getline(cin, str);
    int count_alpha = 0, count_space = 0, count_num = 0, count_other = 0;
    for(const char& c: str) {
        if(isdigit(c)) {
            ++count_num;
        } else if(isalpha(c)) {
            ++count_alpha;
        } else if(c == ' ') {
            ++count_space;
        } else ++count_other;
    }
    cout << count_alpha << endl;
    cout << count_space << endl;
    cout << count_num << endl;
    cout << count_other << endl;
    return 0;
}