Python 基础：控制流程

2.1 条件语句

age = 18

if age >= 18:
    print("成年")
elif age >= 6:
    print("青少年")
else:
    print("儿童")

# 三元表达式
status = "成年" if age >= 18 else "未成年"

2.2 循环

for 循环

# 遍历列表
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(fruit)

# 遍历字典
person = {"name": "Alice", "age": 25}
for key in person:
    print(f"{key}: {person[key]}")

# range 函数
for i in range(5):        # 0,1,2,3,4
    print(i)

for i in range(2, 8):    # 2,3,4,5,6,7
    print(i)

for i in range(0, 10, 2):  # 0,2,4,6,8（步长2）
    print(i)

# enumerate（带索引）
for i, fruit in enumerate(fruits):
    print(f"{i}: {fruit}")

while 循环

count = 0
while count < 5:
    print(count)
    count += 1

# break 和 continue
for i in range(10):
    if i == 3:
        continue  # 跳过 i=3
    if i == 8:
        break     # 退出循环
    print(i)

2.3 match 语句（Python 3.10+）

status = "success"

match status:
    case "success":
        print("操作成功")
    case "error":
        print("操作失败")
    case _:
        print("未知状态")

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