🐍 Python 基础在线学习

# 变量赋值与数据类型 name = "小明" age = 18 height = 1.75 is_student = True print(f"姓名：{name}") print(f"年龄：{age}") print(f"身高：{height}米") print(f"是否学生：{is_student}")

# 成绩评级系统 score = 85 if score >= 90: print("成绩等级：A") elif score >= 80: print("成绩等级：B") elif score >= 60: print("成绩等级：C") else: print("成绩等级：D（需补考）")

# for循环：遍历列表 fruits = ["苹果", "香蕉", "橙子"] for fruit in fruits: print(f"我喜欢吃：{fruit}") # while循环：计算累加 total = 0 i = 1 while i <= 5: total += i i += 1 print(f"1+2+3+4+5 = {total}")

# 列表操作 numbers = [1, 2, 3, 4, 5] print(f"原列表：{numbers}") print(f"第一个元素：{numbers[0]}") print(f"最后三个：{numbers[-3:]}") numbers.append(6) print(f"添加6后：{numbers}") # 元组操作 point = (10, 20) print(f"坐标点：{point}") print(f"X坐标：{point[0]}")

# 字典的创建和访问 student = { "name": "小明", "age": 18, "grade": "高二" } print(f"姓名：{student['name']}") print(f"年龄：{student['age']}") # 添加和修改 student["score"] = 95 student["age"] = 19 print(f"更新后：{student}")

# 定义计算面积的函数 def calculate_area(width, height): """计算矩形面积""" area = width * height return area # 定义问候函数 def greet(name, greeting="你好"): """带默认参数的问候函数""" return f"{greeting}，{name}！" # 调用函数 result = calculate_area(5, 3) print(f"矩形面积：{result}") print(greet("小明")) print(greet("小红", "早上好"))

# 使用StringIO模拟文件操作（浏览器中运行） from io import StringIO # 写入数据 output = StringIO() output.write("第一行数据\n") output.write("第二行数据\n") output.write("第三行数据\n") # 读取数据 output.seek(0) content = output.read() print("文件内容：") print(content) # 按行读取 output.seek(0) for line in output: print(f"读取行: {line.strip()}")