用C++中的string类作为形参统计从键盘输入的字符串中字母、数字、空格和其他字符数的个数

#include <stdio.h>
#include <string.h>

void count(char str[]) {
    int len = strlen(str);
    int letters = 0, digits = 0, spaces = 0, others = 0;
    for(int i = 0; i < len; i++) {
        if(str[i] >= 'a' && str[i] <= 'z' || str[i] >= 'A' && str[i] <= 'Z') {
            letters++;
        } else if(str[i] >= '0' && str[i] <= '9') {
            digits++;
        } else if(str[i] == ' ') {
            spaces++;
        } else {
            others++;
        }
    }
    printf("Letters: %d\n", letters);
    printf("Digits: %d\n", digits);
    printf("Spaces: %d\n", spaces);
    printf("Others: %d\n", others);
}

int main() {
    char str[100];
    printf("Enter a string: ");
    fgets(str, 100, stdin);
    count(str);
    return 0;
}