控制语句

流程控制语句

流程控住语句常用的是 if/else 和 match。

if/else：

a=3
b=5

if a<b:
    print("a<b") # a<b
elif a==b:
    print("a==b")
else:
    print("a>b")

match：

match语句是Python 3.10+引入的新语法。

def http_status(status):
  match status:
    case 200:
      return "OK"
    case 404:
      return "Not Found"
    case 500:
      return "Server Error"
    case _:  # 默认情况
      return "Unknown Status"

print(http_status(200)) # OK
print(http_status(404)) # Not Found
print(http_status(503)) # Unknown Status

循环语句

循环语句一般常用的是 for 循环和 while 循环。

for：

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

# 遍历字符串
for char in "Python":
  print(char) # P y t h o n

# 遍历字典
person = {"name": "Alice", "age": 25, "city": "New York"}
for key, value in person.items():
  print(f"{key}: {value}") # name: Alice age: 25 city: New York

# 遍历范围
for i in range(1, 6):  # 从1到5
  print(i) # 1 2 3 4 5

while：

count = 0
while count < 5:
  # break中断
  if(count == 3):
    break
  print(count) # 0 1 2
  count += 1