Python 控制语句

Python documentation - Control Flow

条件

注意

  • False、None、0、空字符串、()、[]和{}是False其他都是True
  • ==表示值相等，is表示是否是同一个对象
  • 短路逻辑 and和or

使用bool判断值

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bool(1)
> True

bool(0)
> False

if else elif语句

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if num >= 90:
  print('优秀')
elif num >= 60:
  print('及格')
else:
  print('不及格')

断言

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assert age > 0, 'illegal value'

循环

while循环

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# Fibonacci sequence
a, b = 0, 1
while a < 1000:
  print(a)
  a, b = b, a+b

for循环

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# Array
for fruit in ['apple', 'banana', 'mango']:
  print(fruit)

## Range
for i in range(2, 10):
  print(i)

## Dict
coordinate = {'x': 20, 'y': 8, 'z': 16}
for key in coordinate:
  print(coordinate[key])

跳出循环

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break
continue

List comprehension

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[(x, y) for x in range(5) for y in range(3)]