Windows平台C语言非指定时段自动关机：时间比较问题求助

Hey there! Let's work through this time-check and auto-shutdown script for your kid's computer—such a smart way to manage screen time. I’ll break down the time-comparison logic you’re stuck on, then share a complete, tested example.

核心问题：时间比较的简化思路 #

The tricky part with time checks is avoiding messy hour/minute comparisons. The easiest way is to convert all time values (current, start, end) into a single number—total minutes since midnight. This lets you use simple integer comparisons instead of juggling hours and minutes separately.

For example:

• 18:00 becomes 18*60 + 0 = 1080 minutes
• 22:00 becomes 22*60 + 0 = 1320 minutes
• Current time 19:30 becomes 19*60 +30=1170 minutes

Then you just check if the current total minutes fall outside your allowed range.

完整实现代码 #

Here’s a complete script that handles both same-day and cross-day time ranges (in case you ever need overnight access windows):

#include <stdio.h>
#include <time.h>
#include <stdlib.h>

int main() {
    // 自定义允许的时间段：这里设置为18:00到22:00
    const int ALLOWED_START_HOUR = 18;
    const int ALLOWED_START_MIN = 0;
    const int ALLOWED_END_HOUR = 22;
    const int ALLOWED_END_MIN = 0;

    // 获取当前系统时间
    time_t now = time(NULL);
    struct tm *current_time = localtime(&now);
    if (current_time == NULL) {
        perror("Failed to retrieve current time");
        return EXIT_FAILURE;
    }

    // 转换为当日总分钟数
    int current_total_min = current_time->tm_hour * 60 + current_time->tm_min;
    int start_total_min = ALLOWED_START_HOUR * 60 + ALLOWED_START_MIN;
    int end_total_min = ALLOWED_END_HOUR * 60 + ALLOWED_END_MIN;

    // 判断是否超出允许时间范围
    int is_out_of_range = 0;
    if (start_total_min < end_total_min) {
        // 同一天的时间段（比如18:00-22:00）
        is_out_of_range = (current_total_min < start_total_min) || (current_total_min > end_total_min);
    } else {
        // 跨天的时间段（比如22:00-次日6:00）
        is_out_of_range = !(current_total_min >= start_total_min || current_total_min <= end_total_min);
    }

    if (is_out_of_range) {
        printf("当前时间不在允许范围内，系统将在1分钟后关机...\n");
        // 根据你的系统选择对应的关机命令：
        // Windows系统：60秒后关机（需要管理员权限）
        // system("shutdown /s /t 60");
        // Linux/macOS系统：1分钟后关机（需要root权限）
        system("shutdown -h +1");
    } else {
        printf("当前时间在允许范围内，可正常使用电脑。\n");
    }

    return EXIT_SUCCESS;
}

关键细节说明 #

• 时间转换逻辑: Converting to total minutes eliminates edge cases like "current minute is 59 vs start minute 0"—no more weird conditional checks for hour rollover.
• 跨天处理: If you want to allow access from, say, 22:00 to 6:00 the next day, the script automatically handles that by checking if the current time is not between the start and end (since start is larger than end in this case).
• 关机权限: Remember, this script needs to run with admin/root privileges to execute the shutdown command. On Windows, you’ll need to run it as Administrator; on Linux, use sudo.

额外建议 #

• 开机自启动: To make this work automatically, set the script to run on boot:
  • Windows: Add it to Task Scheduler with a trigger for "At log on".
  • Linux: Add a cron job or a systemd service that runs on user login.
• 提前警告: You can adjust the shutdown timer (the /t 60 or +1 part) to give your kid more time to save work—like 10 minutes instead of 1.

内容的提问来源于stack exchange，提问作者user9447673