C语言程序：统计字符类型个数

#include<stdio.h>

int main() {
    char ch;
    int letter = 0, space = 0, other = 0;
    printf('请输入一行字符，直到输入 $ 结束:
');
    while ((ch = getchar()) != '$') {
        if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) {
            letter++;
        } else if (ch == ' ') {
            space++;
        } else {
            other++;
        }
    }
    printf('英文字母个数：%d
空格个数：%d
其他字符个数：%d
', letter, space, other);
    return 0;
}