当输出不应该在else语句中打印时，它会打印出来

Question

所以我对打印输出的顺序有问题。应该是“你有折扣券吗？”那么“是成人票还是儿童票打折？”然后基于该回答或者错误代码或者继续到收据。只有当用户在“您有折扣优惠券吗？”中有一个Y答案时，折扣才会弹出。部分。但是我不能用if和else语句让它工作。

起初，我尝试将所有if和else语句放在一起，但打印的顺序不正确。所以现在我试着在中间插入收据，但这会扰乱if语句的操作，并且打印不正确。无论我输入的是C还是A(这两个字符都是稍后声明的字符，不应该提示打印错误消息)，都会打印错误消息。折扣仍然适用，但不应打印错误消息。

cout<< "\nDo you have a discount coupon (Y for yes)? ";                             
cin>> haveDiscount;

if (haveDiscount == "Y")
{
    cout<< "\nIs the discount for an adult or child's ticket (A for adult, C for child)? ";
    cin>> discountType;
}
if (haveDiscount == "N")
{
    cout<< endl;
}
else
{
    cout<< "\nError: ";
    cout<< discountType;
    cout<<" is not a valid discount type. No discount will be applied.";
}

cout<< "\n\n************************************" << endl;
cout<< right << setw(22) << "Theater Sale";
cout<< "\n************************************";                                            
cout<< "\n\nNumber of adult tickets: " << setw(11) << adultTickets;                         
cout<< "\nNumber of child tickets: " << setw(11) << childTickets << endl;

if (discountType == "A")
{
    coupon = 11.25;
    cout<< "\nDiscount: " << setw(26) << coupon << endl;
}
else
{
    if (discountType == "C")
    {
        coupon = 4.50;
        cout<< "\nDiscount: " << setw(26) << coupon << endl;
    }
}

total = (adultPrice * adultTickets) + (childPrice * childTickets) - coupon;
cout<< "\nTotal purchase: " << setw(20) << total;

我需要在输入C或A时不打印错误消息(这是为折扣声明的)，并且仅在任何其他情况下打印。

Answer 1

如果你缩进你的代码，它更容易阅读。看起来你错过了几个It和elses。现在看起来是这样的：

if (haveDiscount == "Y") 
{
   // ask next question
}
if (haveDiscount == "N") 
{
   // print new line
} 
else 
{
   // print error
}

这意味着无论他们是否有折扣，它都会打印错误。如果haveDiscount不等于"N“，它将打印错误-如果他们在第一个问题中回答"Y”，则总是正确的。你可能想要更多像这样的东西：

if (haveDiscount == "Y") 
{
   // ask next question
   if (discountType == "C" || discountType == "A")
   {
      // do something
   }
   else 
   {
      // print error
   }
}
else 
{
   // print new line
} 

Answer 2

要在discountType不是C或A时打印错误，可能如下所示

if (discountType == "A") 
{
    coupon = 11.25; cout<< "\nDiscount: " << setw(26) << coupon << endl; 
}
else if (discountType == "C")
{
    coupon = 4.50; cout<< "\nDiscount: " << setw(26) << coupon << endl;
}
else
{
    cout<< "\nError: ";
    cout<< discountType;
    cout<<" is not a valid discount type. No discount will be applied."; }
}

如果您希望在打印收据之前打印错误，那么您可以这样做

if (discountType != "C" || discountType != "A")
{
    // Error message
}

在设置了discountType之后的某个位置。