Question

这里的代码极端初学者。阅读John V. Guttag撰写的“使用Python进行计算和编程简介”。最初的问题之一是：

“编写一个检查三个变量-x，y和z-的程序并打印其中最大的奇数。如果它们都不是奇数，那就是应该打印一条消息。“

我提出的代码在第5,7和9行有一个语法错误。由于我是一个完全的初学者，我无法弄明白。建议欢迎！

FirstNumber=int(input("Enter First Number:"))  
SecondNumber=int(input("Enter Second Number:"))  
ThirdNumber=int(input("Enter Third Number:"))  

if (FirstNumber%2!=0:) and (FirstNumber > SecondNumber and FirstNumber > ThirdNumber)  
  print 'First Number is largest odd -> '+str(FirstNumber)  
elif (SecondNumber%2!=0:) and (SecondNumber > FirstNumber and SecondNumber > ThirdNumber)  
  print 'Second Number is largest odd -> '+str(SecondNumber)  
elif (ThirdNumber%2!=0:) and (ThirdNumber > FirstNumber and ThirdNumber > SecondNumber)  
  print 'Third Number is largest odd -> '+str(ThirdNumber)  
else:   
  print 'None are odd -> '+str(FirstNumber), str(SecondNumber), str(ThirdNumber)

Answer 1

如评论中所述，您的代码在每个if和elif语句的末尾都缺少冒号。此外，您的代码在第一个条件测试中具有无关冒号（即(FirstNumber%2!=0:)。

另外，正如您所说，您是初学者，有一些关于简化代码或提高可读性的建议......

firstNum = int(input("Enter First Number: "))  
secondNum = int(input("Enter Second Number: "))  
thirdNum = int(input("Enter Third Number: "))  


# In this case, we don't need the parenthesis. (Sometimes parens are
# required to ensure that the logic works correctly, but in this case,
# we don't.) Python short circuits, meaning it will stop the If 
# statement mid-way as soon as a conditional statement equivocates to False.

if firstNum % 2 != 0 and firstNum > secondNum and firstNum > thirdNum:  
    print 'First Number is largest odd -> ' + str(firsthirdNum)  
elif secondNum % 2 != 0 and secondNum > firstNum and secondNum > thirdNum:  
    print 'Second Number is largest odd -> ' + str(secondNum)  
elif thirdNum % 2 != 0 and thirdNum > firstNum and thirdNum > secondNum: 
    print 'Third Number is largest odd -> ' + str(thirdNum)  
else:   
    print 'None are odd -> ' + str(firstNum), str(secondNum), str(thirdNum)

Answer 2

你忘记了：在python中，if，elif和else总是以'：'结尾当你创建一个函数时。

Answer 3

在:中的每个条件结束时，您需要冒号（if-statement）（而不是每个组成部分的结尾）。这只是你需要知道的语法;没什么特别的。

另外两个不必要的事情是你应该添加一些空格以使操作更清晰，并且可以删除!= 0检查，因为任何整数都不是0评估为True所以会达到同样的效果。最后，不需要括号。

所以这里是更正后的代码：

FirstNumber  = int(input("Enter First Number:"))  
SecondNumber = int(input("Enter Second Number:"))  
ThirdNumber  = int(input("Enter Third Number:"))  

if FirstNumber % 2    and FirstNumber>SecondNumber and FirstNumber>ThirdNumber:
  print 'First Number is largest odd -> '+str(FirstNumber)  
elif SecondNumber % 2 and SecondNumber>FirstNumber and SecondNumber>ThirdNumber:
  print 'Second Number is largest odd -> '+str(SecondNumber)  
elif ThirdNumber % 2  and ThirdNumber>FirstNumber  and ThirdNumber>SecondNumber:
  print 'Third Number is largest odd -> ' + str(ThirdNumber)  
else:   
  print 'None are odd -> ' + str(FirstNumber), str(SecondNumber), str(ThirdNumber)

语法错误，初级Python 2.1代码

3 个答案: