谈谈Python中的while循环语句

# 输入提示
prompt = '输入一个数字，我将告诉你，它是奇数，还是偶数哦O(∩_∩)O~'
prompt += '\n输入“不玩了”，将退出本程序： '

exit = '不玩了' # 退出指令
content = '' #输入内容
while content != exit:
 content = input(prompt)
 if content.isdigit():
  number = int(content)
  if (number % 2 == 0):
   print('该数是偶数')
  else:
   print('该数是奇数')
 elif content != exit:
  print('输入的必须是数字哦')

prompt = '输入一个数字，我将告诉你，它是奇数，还是偶数哦O(∩_∩)O~'
prompt += '\n输入“不玩了”，将退出本程序： '

exit = '不玩了' # 退出指令
content = '' # 输入内容
active = True # 活动状态标识
while active:
 content = input(prompt)
 if content.isdigit():
  number = int(content)
  if (number % 2 == 0):
   print('该数是偶数')
  else:
   print('该数是奇数')
 elif content == exit:
  active = False
 else:
  print('输入的必须是数字哦')

...
while active:
 content = input(prompt)
 if content.isdigit():
  ...
 elif content == exit:
  break
 else:
  ...

while active:
 content = input(prompt)
 if content.isdigit():
  number = int(content)
  if (number % 2 == 0):
   print('该数是偶数')
  else:
   continue
 elif content == exit:
  break
 else:
  print('输入的必须是数字哦')

to_go_countries = ['英国', '法国', '美国'] # 想去的国家
visited_countries = [] # 已去的国家
while to_go_countries:
 country = to_go_countries.pop()
 print('准备去【' + country+'】')
 print('【1】做攻略')
 print('【2】出发')
 print('【3】回来咯')
 visited_countries.append(country)

print('to_go_countries:'+str(to_go_countries))
print('这些国家去过啦：' + str(visited_countries))

foods = ['拌海蜇', '炝冬笋', '炸豆腐', '炸面筋', '麻辣野鸡', '炒肉片']
while '炸豆腐' in foods:
 foods.remove('炸豆腐')
print('foods=' + str(foods))