C++统计字符串中各类型字符的个数

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

int main() {

    int letter = 0;
    int digit = 0;
    int space = 0;
    int other = 0;
    
    char buf[1024] = {0};
    cin.getline(buf, sizeof(buf));

    // write your code here......
    for(int i = 0; buf[i] != '\0'; i++){ //遍历字符串到'\0'为止
        char c = buf[i];
        if(c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z') //大小写字母
            letter++;
        else if(c >= '0' && c <= '9') //数字
            digit++;
        else if(c == ' ')  //空格
            space++; 
        else //其他字符
            other++;
    }
    cout << "letter:" << letter << " digit:" << digit << " space:" << space << " other:" << other << endl;

	return 0;
}

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

int main() {

    int letter = 0;
    int digit = 0;
    int space = 0;
    int other = 0;
    
    char buf[1024] = {0};
    cin.getline(buf, sizeof(buf));

    // write your code here......
    int len = strlen(buf);
    for(int i = 0;i < len; i++){
        if(isalpha(buf[i])){
            letter++;
        }else if(isdigit(buf[i])){
            digit++;
        }else if(isspace(buf[i])){
            space++;
        }else{
            other++;
        }
    }
    cout << "letter:" << letter << " digit:" << digit << " space:" << space << " other:" << other << endl;

	return 0;
}