用C语言输入一串字符，分别统计其中英文字母，数字，空格和其他字符的个数

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

int main()
{
    char str[1000];
    int i, alpha, digit, space, other;

    alpha = digit = space = other = i = 0;

    printf("Enter a string: ");
    gets(str);

    while(str[i] != '\0')
    {
        if(isalpha(str[i]))
        {
            alpha++;
        }
        else if(isdigit(str[i]))
        {
            digit++;
        }
        else if(str[i] == ' ')
        {
            space++;
        }
        else
        {
            other++;
        }

        i++;
    }

    printf("Number of alphabets: %d\n", alpha);
    printf("Number of digits: %d\n", digit);
    printf("Number of spaces: %d\n", space);
    printf("Number of other characters: %d\n", other);

    return 0;
}