python的switch实现

发布时间:2022-03-01 09:35:10 人气:47 作者:多测师

  python中没有现成的swith --- case 控制流,可以通过如下方法实现:

  一:通过字典实现

  type="sms"

  advtype={

  "sms":"select id from advertising where dtype like 'SMSAdvertising' ORDER BY RAND() limit 0,1",

  "mms":"select id from advertising where dtype like 'MMSAdvertising' ORDER BY RAND() limit 0,1",

  "mma":"select id from advertising where dtype like 'MMAAdvertising' ORDER BY RAND() limit 0,1",

  "page":"select id from advertising where dtype like 'PageAdvertising' ORDER BY RAND() limit 0,1",

  "installer":"select id from advertising where dtype like 'InstallerAdvertising' ORDER BY RAND() limit 0,1"

  }

  print advtype.get(type.lower())

python的switch实现

  二、通过自编类或者函数实现(这个有点麻烦,但是也更灵活)

  class switch(object):

  def __init__ (self,value): #初始化需要匹配的值value

  self.value=value

  self.fall=False #如果匹配到的case语句中没有break,则fall为true.

  def __iter__ (self):

  yield self.match #调用match方法,来返回一个生成器

  raise StopIteration #StopIteration异常来判断for循环是否结束

  def match (self,*args):

  if self.fall or not args: #模拟case子句的方法

  return True #如果fall为true,则继续执行下面的case子句或case子句没有匹配项,则流转到默认分支

  elif self.value in args: #匹配成功

  self.fall=True

  return True

  else: #匹配失败

  return False

  operator="+"

  x=1

  y=2

  for case in switch(operator):

  if case("+"):

  print x+y

  break

  if case("-"):

  print x-y

  break

  if case("*"):

  print x*y

  break

  if case("/"):

  print x/y

  break

  else:

  print ""

  以上内容为大家介绍了python的switch实现,希望对大家有所帮助,如果想要了解更多Python相关知识,请关注多测师。https://www.e70w.com/xwzx/

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