C语言输入一行字符，分别统计出其中英文字母、数字、空格和其他字符的个数。

#include <stdio.h>
#include <ctype.h>

int main() {
    char str[100];
    int i, alpha_count = 0, digit_count = 0, space_count = 0, other_count = 0;

    printf("Enter a string: ");
    fgets(str, 100, stdin);

    for (i = 0; str[i] != '\0'; i++) {
        if (isalpha(str[i])) {
            alpha_count++;
        } else if (isdigit(str[i])) {
            digit_count++;
        } else if (isspace(str[i])) {
            space_count++;
        } else {
            other_count++;
        }
    }

    printf("Number of alphabets: %d\n", alpha_count);
    printf("Number of digits: %d\n", digit_count);
    printf("Number of spaces: %d\n", space_count);
    printf("Number of other characters: %d\n", other_count);

    return 0;
}