如果循环中存在循环，如何中断程序？

Question

我一直在试图用Python做一个对数计算器。我离完成它只有一步之遥。下面是代码：

import math 
print("Welcome to logarithm calculator") 

while True: 
    try: 
     inlog = int(input("Enter any value greater than zero to lookup its logarithm to the base 10\n")) 
     outlog = math.log(inlog, 10) 
     print(outlog) 

     # Here, the program will ask the user to quit or to continue 
     print("Want to check another one?") 
     response = input("Hit y for yes or n for no\n") 

     if response == ("y" or "Y"): 
      pass 
     elif response == ("n" or "N"): 
      break 
     else: 
      #I don't know what to do here so that the program asks the user to quit or continue if the response is invalid? 

    except ValueError: 
     print("Invalid Input: Make sure your number is greater than zero and no alphabets. Try Again.") 

else语句后，我希望程序要求用户一次又一次地做出反应，直到它为“Y”或“Y”和“N”或有效的反应“ N”。如果我在这里添加另一个while循环，如果用户输入“y”，那么对于pass语句会很有帮助。但是当用户响应为“n”时它不会中断程序，因为它会将我们置于外部循环中。 那么如何整理呢？

Answer 1

你可以做这样的事情：

stop=False 
while True: 
    try: 
     inlog = int(input("Enter any value greater than zero to lookup its logarithm to the base 10\n")) 
     outlog = math.log(inlog, 10) 
     print(outlog) 

     # Here, the program will ask the user to quit or to continue 
     print("Want to check another one?") 

     while True: 
      response = input("Hit y for yes or n for no\n") 
      if response == ("y" or "Y"): 
       stop = False 
       break 
      elif response == ("n" or "N"): 
       stop = True 
       break 
      else: 
       continue 
     if stop: 
      break 
except ValueError: 
     print("Invalid Input: Make sure your number 

Answer 2

您可以在初始值为'false'的值之外定义一个布尔参数。在外循环的每次运行开始时，您可以检查此布尔值，如果它为真，那么也会打破外循环。在此之后，当你想要在内部循环内部结束外部循环时，只需在打破内部循环之前使值为真。这种方式外环也将打破。

Answer 3

您可以在测试移动到不同的功能：

def read_more(): 
    while True: 
     print("Want to check another one?") 
     response = input("Hit y for yes or n for no\n") 

     if response == ("y" or "Y"): 
      return True 
     elif response == ("n" or "N"): 
      return False 
     else: 
      continue 

然后在你的函数，只是测试这种方法的返回类型：

while True: 
    try: 
     inlog = int(input("Enter any value greater than zero to lookup its logarithm to the base 10\n")) 
     outlog = math.log(inlog, 10) 
     print(outlog) 

     if read_more(): 
      continue 
     else: 
      break 

需要注意的是，你可以进入无限循环，如果用户继续输入错误的输入。你可以限制他达到一些最大的尝试。

Answer 4

试试这个：

import math 
class quitit(Exception): 
    pass 
print("Welcome to logarithm calculator") 

while True: 
    try: 
     inlog = int(input("Enter any value greater than zero to lookup its logarithm to the base 10\n")) 
     outlog = math.log(inlog, 10) 
     print(outlog) 

     # Here, the program will ask the user to quit or to continue 
     print("Want to check another one?") 
     while True: 
      response = input("Hit y for yes or n for no\n") 
      if response == ("y" or "Y"): 
       break 
      elif response == ("n" or "N"): 
       raise quitit 
except quitit: 
     print "Terminated!"   
except ValueError: 
     print("Invalid Input: Make sure your number is greater than zero and no alphabets. Try Again.") 

Answer 5

如果用户输入小于或等于零的数量，这将产生一个异常，你有没有占了。

只要突破循环，它不会嵌套，你不能已经爆发。如果你有更深的嵌套，那么我会建议使用下面的模板来打破嵌套循环。

def loopbreak(): 
    while True: 
    while True: 
     print('Breaking out of function') 
     return 
    print('This statement will not print, the function has already returned') 

Answer 6

stop=False 
while not stop: 
    try: 
     inlog = int(input("Enter any value greater than zero to lookup its logarithm to the base 10\n")) 
     outlog = math.log(inlog, 10) 
     print(outlog) 

     # Here, the program will ask the user to quit or to continue 
     print("Want to check another one?") 

     while True: 
      response = raw_input("Hit y for yes or n for no\n") 
      if response == ("y" or "Y"): 
       break 
      elif response == ("n" or "N"): 
       stop = True 
       break 
    except ValueError: 
     print("Invalid Input: Make sure your number")