如果循環中存在循環，如何中斷程序？

Question

我一直在試圖用Python做一個對數計算器。我離完成它只有一步之遙。下面是代碼：

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語句後，我希望程序要求用戶一次又一次地做出反應，直到它爲「Y」或「Y」和「N」或有效的反應「 N」。如果我在這裏添加另一個while循環，如果用戶輸入「y」，那麼對於pass語句會很有幫助。但是當用戶響應爲「n」時它不會中斷程序，因爲它會將我們置於外部循環中。 那麼如何整理呢？

Answer 1

你可以做這樣的事情：

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

您可以在初始值爲'false'的值之外定義一個布爾參數。在外循環的每次運行開始時，您可以檢查此布爾值，如果它爲真，那麼也會打破外循環。在此之後，當你想要在內部循環內部結束外部循環時，只需在打破內部循環之前使值爲真。這種方式外環也將打破。

Answer 3

您可以在測試移動到不同的功能：

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 

然後在你的函數，只是測試這種方法的返回類型：

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，你可以進入無限循環，如果用戶繼續輸入錯誤的輸入。你可以限制他達到一些最大的嘗試。

Answer 4

試試這個：

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

如果用戶輸入小於或等於零的數量，這將產生一個異常，你有沒有佔了。

只要突破循環，它不會嵌套，你不能已經爆發。如果你有更深的嵌套，那麼我會建議使用下面的模板來打破嵌套循環。

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")