98 lines
3.0 KiB
Python
98 lines
3.0 KiB
Python
# 第 1-4 课示例：运算符
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#
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# 本文件按类别演示常用运算符。
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# 运行时请对照每段注释，观察不同运算符产生的结果和数据类型。
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# 一、算术运算符
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first_number = 17
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second_number = 7
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print(f"加法：{first_number + second_number}")
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print(f"减法：{first_number - second_number}")
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print(f"乘法：{first_number * second_number}")
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print(f"普通除法：{first_number / second_number}")
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print(f"整除：{first_number // second_number}")
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print(f"取余：{first_number % second_number}")
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print(f"幂运算：{2 ** 3}")
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# 二、整除与取余的实际含义
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# 17 天中包含 2 个完整星期，另外还剩 3 天。
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learning_days = 17
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full_weeks = learning_days // 7
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remaining_days = learning_days % 7
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print(f"{learning_days} 天等于 {full_weeks} 个完整星期加 {remaining_days} 天。")
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# 三、字符串支持的部分运算
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# 加号连接字符串，乘号让字符串重复指定次数。
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role_name = "Agent" + " " + "开发者"
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separator = "=" * 20
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print(role_name)
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print(separator)
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# 四、比较运算符
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completed_hours = 12
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target_hours = 10
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print(f"是否等于目标：{completed_hours == target_hours}")
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print(f"是否不等于目标：{completed_hours != target_hours}")
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print(f"是否超过目标：{completed_hours > target_hours}")
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print(f"是否少于目标：{completed_hours < target_hours}")
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print(f"是否达到目标：{completed_hours >= target_hours}")
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print(f"是否未超过目标：{completed_hours <= target_hours}")
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# 五、复合赋值运算符
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# completed_tasks += 1 等价于 completed_tasks = completed_tasks + 1。
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completed_tasks = 3
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completed_tasks += 1
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print(f"新增一个完成项后：{completed_tasks}")
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# 下面把预计时间扩大为原来的两倍。
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estimated_hours = 5
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estimated_hours *= 2
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print(f"调整后的预计时间：{estimated_hours}")
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# 六、逻辑运算符
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course_finished = True
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practice_finished = True
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uses_pycharm = True
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uses_vscode = False
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can_start_next_course = course_finished and practice_finished
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has_code_editor = uses_pycharm or uses_vscode
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is_still_learning = not course_finished
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print(f"课程和练习是否都完成：{can_start_next_course}")
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print(f"是否至少使用一种编辑器：{has_code_editor}")
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print(f"是否仍未完成课程：{is_still_learning}")
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# 七、比较运算与逻辑运算组合
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daily_hours = 2.5
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completed_tasks = 4
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is_plan_healthy = (daily_hours >= 1) and (completed_tasks >= 3)
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print(f"学习时长和任务数是否同时达标：{is_plan_healthy}")
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# 八、运算优先级
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# 第一个结果先计算乘法；第二个结果先计算括号中的加法。
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result_without_parentheses = 2 + 3 * 4
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result_with_parentheses = (2 + 3) * 4
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print(f"没有括号：{result_without_parentheses}")
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print(f"使用括号：{result_with_parentheses}")
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# 九、观察浮点数精度现象
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# 这个结果说明部分十进制小数无法用二进制浮点数精确表示。
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floating_point_result = 0.1 + 0.2
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print(f"0.1 + 0.2 的结果：{floating_point_result}")
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