根据用户输入选择正确的else语句

我正在开发一个小程序，用户输入一个价格，然后程序会根据输入输出运输成本。根据用户输入选择正确的else语句

#Initilaize variables 

lowUS = 6.00; 
medUS = 9.00; 
highUS = 12.00; 
lowCan = 8.00; 
medCan = 12.00; 
highCan = 15.00; 

#Greet user and ask for input 
print("Welcome to Ben's shipping calculator!"); 
print("We will calculate your shipping cost for you!"); 


orderTotal = float(input("Please input your total amount.")); 
country = input("In which country do you reside? Please type C for Canada or U or USA. "); 

#Validate input 
while country not in {'u', 'c', 'C', 'U'}: 
    print ("Invalid input. Please try again. ") 
    country = input("In which country do you reside? Please type C for Canada or U or USA. "); 

#Determine how much the shipping fee is 
if country == 'U' or country == 'u': 
    if orderTotal <= 50.00: 
     if orderTotal > 50.00 and orderTotal <= 100.00: 
      if orderTotal > 100.00 and orderTotal <= 150.00: 
       if orderTotal > 150.00: 
        print("Your shipping is free and your grand total is", orderTotal) 
       else: 
        print("Your shipping fee is: ", highUS); 
        orderTotal = (orderTotal + highUS); 
      else: 
       print("Your shipping fee is: ", medUS); 
       orderTotal = (orderTotal + medUS); 
     else: 
      print("Your shipping fee is: ", lowUS); 
      orderTotal = (orderTotal + lowUS); 

elif country == 'c' or country == 'C': 
    if orderTotal <= 50.00: 
     if orderTotal > 50.00 and orderTotal <= 100.00: 
      if orderTotal > 100.00 and orderTotal <= 150.00: 
       if orderTotal > 150.00: 
        print("Your shipping is free and your grand total is", orderTotal) 
       else: 
        print("Your shipping fee is: ", highCan); 
        orderTotal = (orderTotal + highCan); 
      else: 
       print("Your shipping fee is: ", medCan); 
       orderTotal = (orderTotal + medCan); 
     else: 
      print("Your shipping fee is: ", lowCan); 
      orderTotal = (orderTotal + lowCan); 

print("Your grand total is: $", orderTotal);

我很新的蟒蛇和编程，我不知道这是去它的好方法，但我学习if-else语句，所以我想我会试试看。到目前为止，只有当您输入金额为“50”时才有效。它将根据国家计算仅为“50”。我不确定我出错的地方，如果有人能帮忙解释，那会很好。

来源

2016-09-21 legendaryxv2

你的第一个'if'只有在它小于或等于50时才进入......你做的下一个检查是如果它大于50，那么它将不会执行......因此， 'else'子句是唯一可以执行的子句... –

Python除了换行符外没有行结束符 - 这些分号完全没有必要。这不是C！（或Java，或JavaScript，或其他任何东西） – MattDMo

你的第一个if只有在它小于或等于50时才会进入下一个检查是否它大于50它不能被执行...所以你的else子句是唯一可以执行的语句......基本上，嵌套的if语句不会执行，因为这样做的条件已从排除的if中排除。

你最好的重组逻辑：

if orderTotal > 150: 
    # do something 
elif orderTotal > 100: 
    # do something 
elif orderTotal > 50: 
    # do something 
else: # 50 or under... 
    # do something else

来源

2016-09-21 19:41:34

好吧，我现在看到了这个错误，我实际上正在考虑这样做，但并非100％确定它是否正确。谢谢！ – legendaryxv2

您的逻辑是有点扭曲。如果量< = $ 50时，那么它是不是> $ 50或< = $ 100所以任何下面是嵌套“如果”永远不会执行：

if orderTotal <= 50.00: 
    if orderTotal > 50.00 and orderTotal <= 100.00: 
     # ** this will never run ** 
    else: 
     # This will run, if orderTotal <= 50.00

什么都不会发生，如果orderTotal > 50.00，因为没有else为if orderTotal <= 50.00测试。 @Jon Clements的答案显示了构建代码的正确方法。

来源

2016-09-21 19:47:15 BrianO

根据用户输入选择正确的else语句

回答

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