Python条件判断案例如何编写代码

wen python案例 2026-07-01 202

本文目录导读：

Python条件判断案例如何编写代码

基础条件判断案例
实用案例
复杂业务逻辑案例
简化代码技巧
编写建议

我来为你介绍几个Python条件判断的实用案例,从基础到进阶：

基础条件判断案例

案例1：判断成绩等级

# 根据分数判断等级
score = int(input("请输入成绩（0-100）："))
if score >= 90:
    print("优秀")
elif score >= 80:
    print("良好")
elif score >= 70:
    print("中等")
elif score >= 60:
    print("及格")
else:
    print("不及格")
# 更严谨的写法，包含输入验证
if 0 <= score <= 100:
    if score >= 90:
        print("优秀")
    elif score >= 80:
        print("良好")
    elif score >= 70:
        print("中等")
    elif score >= 60:
        print("及格")
    else:
        print("不及格")
else:
    print("请输入0-100之间的分数")

案例2：判断闰年

year = int(input("请输入年份："))
# 判断闰年条件：能被4整除但不能被100整除，或者能被400整除
if (year % 4 == 0 and year % 100 != 0) or (year % 400 == 0):
    print(f"{year}年是闰年")
else:
    print(f"{year}年是平年")

实用案例

案例3：登录验证系统

# 模拟登录验证
username = input("请输入用户名：")
password = input("请输入密码：")
# 预设的用户名和密码
correct_username = "admin"
correct_password = "123456"
# 条件判断
if username == correct_username and password == correct_password:
    print("登录成功！欢迎回来")
elif username != correct_username:
    print("用户名错误")
elif password != correct_password:
    print("密码错误")
else:
    print("登录失败")

案例4：温度转换与提示

temperature = float(input("请输入温度："))
unit = input("请输入温度单位 (C/F)：").upper()
if unit == "C":
    # 摄氏度转华氏度
    fahrenheit = (temperature * 9/5) + 32
    print(f"{temperature}°C = {fahrenheit:.1f}°F")
    # 温度提示
    if temperature >= 35:
        print("⚠️ 高温预警！注意防暑")
    elif temperature >= 25:
        print("☀️ 天气炎热，适合游泳")
    elif temperature >= 15:
        print("🌤️ 天气舒适，适合户外活动")
    elif temperature >= 5:
        print("🌥️ 天气凉爽，注意添衣")
    else:
        print("❄️ 天气寒冷，注意保暖")
elif unit == "F":
    # 华氏度转摄氏度
    celsius = (temperature - 32) * 5/9
    print(f"{temperature}°F = {celsius:.1f}°C")
else:
    print("请输入正确的温度单位 (C 或 F)")

复杂业务逻辑案例

案例5：购物折扣计算器

# 根据购买金额和会员等级计算折扣
total_amount = float(input("请输入购物总金额："))
membership = input("请输入会员等级 (普通/银卡/金卡/钻石)：")
# 判断折扣
if total_amount >= 1000:
    if membership == "钻石":
        discount = 0.7  # 7折
        points = total_amount * 2  # 双倍积分
    elif membership == "金卡":
        discount = 0.8  # 8折
        points = total_amount * 1.5
    elif membership == "银卡":
        discount = 0.85  # 85折
        points = total_amount * 1.2
    else:
        discount = 0.9  # 9折
        points = total_amount
elif total_amount >= 500:
    if membership == "钻石":
        discount = 0.75
        points = total_amount * 1.8
    elif membership == "金卡":
        discount = 0.85
        points = total_amount * 1.3
    elif membership == "银卡":
        discount = 0.9
        points = total_amount * 1.1
    else:
        discount = 0.95
        points = total_amount
else:
    if membership == "钻石":
        discount = 0.8
        points = total_amount * 1.5
    elif membership == "金卡":
        discount = 0.88
        points = total_amount * 1.2
    else:
        discount = 1.0  # 不打折
        points = total_amount
final_amount = total_amount * discount
print(f"原价：¥{total_amount:.2f}")
print(f"折扣：{int((1-discount)*100)}%")
print(f"实付：¥{final_amount:.2f}")
print(f"获得积分：{int(points)}")

案例6：BMI健康评估系统

# 计算BMI指数并给出健康建议
height = float(input("请输入身高（米）："))
weight = float(input("请输入体重（公斤）："))
# 计算BMI
bmi = weight / (height ** 2)
print(f"您的BMI指数为：{bmi:.1f}")
# 判断健康状况
if bmi < 18.5:
    print("⚠️ 体重过轻")
    advice = "建议增加营养摄入，适当锻炼增肌"
elif bmi < 24:
    print("✅ 体重正常")
    advice = "请保持健康的饮食习惯和运动"
elif bmi < 28:
    print("⚠️ 超重")
    advice = "建议控制饮食，增加运动量"
elif bmi < 32:
    print("❌ 肥胖（一级）")
    advice = "建议专业健康指导，合理饮食配合运动"
elif bmi < 37:
    print("❌ 肥胖（二级）")
    advice = "建议咨询医生，制定科学的减重计划"
else:
    print("‼️ 极度肥胖（三级）")
    advice = "强烈建议寻求医疗帮助，进行专业干预"
print(f"健康建议：{advice}")

简化代码技巧

使用三元运算符

# 传统写法
age = 20
if age >= 18:
    status = "成年"
else:
    status = "未成年"
# 三元运算符写法
status = "成年" if age >= 18 else "未成年"

使用字典优化条件判断

# 代替多个if-elif
def get_day_name(day_number):
    days = {
        1: "星期一",
        2: "星期二", 
        3: "星期三",
        4: "星期四",
        5: "星期五",
        6: "星期六",
        7: "星期日"
    }
    return days.get(day_number, "无效的输入")
print(get_day_name(3))  # 输出：星期三