如何結束while循環並跳過for循環？

Question

如果用戶輸入'否'，程序將不會通過for循環。如果用戶輸入'no'，我不希望它tmpfile.write（行）。

def remove(): 
    coname = raw_input('What company do you want to remove? ') # company name 
    f = open('codilist.txt') 
    tmpfile = open('codilist.tmp', 'w') 
    for line in f: 
     if coname.upper() in line: 
      while True: 
       answer = raw_input('Are you sure you want to remove ' + line.upper() + '?') 
       if answer == 'yes': 
        print line.upper() + '...has been removed.'    
       elif answer == 'no': 
        break # HERE IS WHERE I NEED HELP 
       else: 
        print 'Please choose yes or no.'     
     else: 
      tmpfile.write(line) 
    else: 
     print 'Company name is not listed.' 
    f.close() 
    tmpfile.close() 
    os.rename('codilist.tmp', 'codilist.txt') 

Answer 1

設置一個標誌變量，然後跳出while循環。然後在for循環中，檢查標誌是否設置，然後中斷。

PS：如果是不循環

Answer 2

你必須把整個for循環的功能和使用return擺脫它：

def find_and_remove(f,coname,tmpfile): 
    for line in f: 
     if coname.upper() in line: 
      while True: 
       answer = raw_input('Are you sure you want to remove ' + line.upper() + '?') 
       if answer == 'yes': 
        print line.upper() + '...has been removed.'    
       elif answer == 'no': 
        return # HERE IS WHERE I NEED HELP 
       else: 
        print 'Please choose yes or no.'     
     else: 
      tmpfile.write(line) 
    else: 
     print 'Company name is not listed.' 

def remove(): 
    coname = raw_input('What company do you want to remove? ') # company name 
    f = open('codilist.txt') 
    tmpfile = open('codilist.tmp', 'w') 
    find_and_remove(f,coname,tmpfile) 
    f.close() 
    tmpfile.close() 
    os.rename('codilist.tmp', 'codilist.txt') 

Answer 3

要做到這一點最簡單的方法是創建一個獲取用戶輸入的函數：

def get_yes_or_no(message): 
    while True: 
     user_in = raw_input(message).lower() 
     if user_in in ("yes", "no"): 
      return user_in 

並修改您的原始功能，如下所示：

def remove(): 
    coname = raw_input('What company do you want to remove? ') # company name 
    f = open('codilist.txt') 
    tmpfile = open('codilist.tmp', 'w') 
    for line in f: 
     if coname.upper() in line: 
      answer = get_yes_or_no('Are you sure you want to remove ' + line.upper() + '?') 
      #answer logic goes here    
     else: 
      tmpfile.write(line) 
    else: 
     print 'Company name is not listed.' 
    f.close() 
    tmpfile.close() 
    os.rename('codilist.tmp', 'codilist.txt') 

Answer 4

而不是使用一個無限循環和break荷蘭國際集團，當你跳行，這三種情況（跳過，刪除和無效的答覆）在循環條件使用標誌區分。您將該標誌設置爲退出跳轉案例中的循環，中止刪除案例，並將該標誌按原樣保留在無效答案中。這使您可以使用while的else子句（如果while由於條件變爲false而退出，則會觸發該子句）檢測跳過事例。從那裏，你可以跳到for循環的下一個迭代，使用continue（或者跳過所有其餘的行使用break - 從你打算的問題來看，這不是很清楚，但區別在於關鍵字的變化） ：

for line in f: 
    if coname.upper() in line: 
     answered = False 
     while not answered: 
      answer = raw_input('Are you sure you want to remove ' + line.upper() + '?') 
      if answer == 'yes': 
       print line.upper() + '...has been removed.' 
       break 
      elif answer == 'no': 
       answered = True # HERE IS WHERE I NEED HELP 
      else: 
       print 'Please choose yes or no.' 
     else: 
      continue 
    else: 
     tmpfile.write(line) 
else: 
    print 'Company name is not listed.' 

Answer 5

Python有例外，您可以使用它來代替GOTO類型的構造。

class Breakout(Exception): 
    pass 

def remove(): 
    coname = raw_input('What company do you want to remove? ') # company name 
    f = open('codilist.txt') 
    tmpfile = open('codilist.tmp', 'w') 
    try: 
     for line in f: 
      if coname.upper() in line: 
       while True: 
        answer = raw_input('Are you sure you want to remove ' + line.upper() + '?') 
        if answer == 'yes': 
         print line.upper() + '...has been removed.' 
        elif answer == 'no': 
         raise Breakout() 
        else: 
         print 'Please choose yes or no.' 
      else: 
       tmpfile.write(line) 
     else: 
      print 'Company name is not listed.' 
    except Breakout: 
     pass 

    f.close() 
    tmpfile.close() 
    os.rename('codilist.tmp', 'codilist.txt') 

請注意，在那裏中間引發異常。