Question

我正在尝试制作代码，以便书籍数量决定每个语句的用法。因此，如果我写20，预期的答案应该是95，而不是100。这意味着elif被忽略，并且只执行if语句（除了负的elif语句）。如何重写代码，使其不会忽略Book＆gt; 10和书＆gt; 20个elif陈述？

try:  
  book = raw_input('Enter amount of Books:\n')  
  Book = int(book)  
  red = Book - 10  

  if Book > 0:  
    print int(book) * 5  
  elif Book > 10:  
    print (red * 4.5) + (10 * 5)  
  elif Book < 0:  
    print ('Amount cannot be negative.')  
  elif Book > 20:  
    print (10 * 5) + (10 * 4.5) + (int(book) - 20 ) * 4  
  else:  
    print ('There has been a mistake. Please restart.')

except:  
  print ('Error.')

Answer 1

elif语句意味着，如果，这意味着仅在第一个语句错误时评估语句，在您的情况下if book>0为真且结果为100：其他条件未被评估。

你只需要修改你的条件顺序，也要注意你的缩进：

try:  
    book = raw_input('Enter amount of Books:\n')  
    Book = int(book)  
    red = Book - 10  

    if Book > 20:
        print (10 * 5) + (10 * 4.5) + (int(book) - 20 ) * 4
    elif Book > 10:  
        print (red * 4.5) + (10 * 5)  
    elif Book > 0:
       print int(book) * 5   
    elif Book < 0:  
       print ('Amount cannot be negative.')  
    else:  
       print ('There has been a mistake. Please restart.')

except:  
    print ('Error.')

Answer 2

您的第一个if语句将始终捕获n > 10和n > 20的情况。因此，您的条件应以基本情况开始;一个不容易实现的，例如：

if Book < 0:  
  print ('Amount cannot be negative.')

继续向前查看将首先捕获的案例，因为条件的顺序在您的案例中很重要，因为它们不是互斥的，即n > 20。因此代码看起来如下所示：

if Book < 0:  
  print ('Amount cannot be negative.')
elif Book > 20:  
  print (10 * 5) + (10 * 4.5) + (int(book) - 20 ) * 4
elif Book > 10:  
  print (red * 4.5) + (10 * 5)
elif Book > 0:  
  print int(book) * 5
else:
  print ('There has been a mistake. Please restart.')

Answer 3

try:  
    book = raw_input('Enter amount of Books:\n')  
    Book = int(book)  
    red = Book - 10 
    if Book < 0:
        print ('Amount cannot be negative.')
    else:
        if Book > 20:  
            print 50 + 45 + (Book - 20) * 4
        elif Book > 10:
            print (red * 4.5) + (10 * 5)
        elif Book > 0:  
            print Book * 5  
        else:  
            print ('There has been a mistake. Please restart.')
except:  
    print ('Error.')

Answer 4

尝试尽可能消除边缘情况。

放"/AUTOSAR/EcucDefs/Com/ComConfig/ComIPdu/ComIPduCancellationSupport"涵盖所有大于10的值。范围：[10，）
因此，在此之后放置public String someMethod(String parm1, String parm2) { final Function<String, Boolean> isValidString = parm -> parm.equals("Test") || parm.equals("Test2"); ... String parm1 = ... if (parm1 != null && isValidString.apply(parm)) { ... do something } ...并不重要。

根据优先顺序陈述你的陈述。

Book > 10

Python忽略了elif语句

4 个答案: