核心逻辑

判断输入字符的类型：

• 大写字母（A-Z）→ 输出 "upper"
• 小写字母（a-z）→ 输出 "lower"
• 数字字符（0-9）→ 输出 "digit"
• 其他字符 → 输出 "other"

代码实现

C

#include <stdio.h>

int main() {
    char c;
    scanf("%c", &c);
    
    if (c >= 'A' && c <= 'Z') {
        printf("upper\n");
    } else if (c >= 'a' && c <= 'z') {
        printf("lower\n");
    } else if (c >= '0' && c <= '9') {
        printf("digit\n");
    } else {
        printf("other\n");
    }
    
    return 0;
}

C++

#include <bits/stdc++.h>
using namespace std;

int main() {
    char c;
    cin >> c;
    
    if (c >= 'A' && c <= 'Z') {
        cout << "upper" << endl;
    } else if (c >= 'a' && c <= 'z') {
        cout << "lower" << endl;
    } else if (c >= '0' && c <= '9') {
        cout << "digit" << endl;
    } else {
        cout << "other" << endl;
    }
    
    return 0;
}

Python

c = input().strip()  # 读取输入的单个字符
if c.isupper():
    print("upper")
elif c.islower():
    print("lower")
elif c.isdigit():
    print("digit")
else:
    print("other")