案例切換中的表達式無效

Question

這一直使我發瘋。

private void BtnMix_Click(object sender, EventArgs e)
{
   //Declare the variables to be used in the process
    String Color1;
    String Color2;

    //Determine whether or not a selection has been bade
    if (Colorlist1.SelectedIndex != -1 && ColorList2.SelectedIndex != -1) 
    {
        //Get the selected colors
        Color1 = Colorlist1.SelectedItem.ToString();
        Color2 = ColorList2.SelectedItem.ToString();

        //Determine the correct result
        switch (Color1 +|+ Color2)
        {
            case "Red|Red":
                lblResult.Text = "Red";
                break;
            case "Red|Blue":
                Lblresult.text ="Purple";
                break;
            case "Red|Yellow":
                lblresult.text = "Orange";
                break;
            case "Blue|Red":
                lblresult.text = "Purple";
                break;
            case "Blue|Blue":
                lblresult.text = "Blue";
                break;
            case "Blue|Yellow":
                lblresult.text = "Green";
                break;
            case "Yellow|Red":
                lblresult.text = "Orange";
                break;
            case "Yellow|Blue":
                lblresult.text = "Green";
                break;
            case "Yellow|Yellow":
                lblresult.text = "Yellow";
                break;
        }
    }
    else
    {
        MessageBox.Show("Please select two colors");
    }
}

我知道我很想念一些簡單的事情，但是對於我的一生，我無法弄清楚。 到目前為止，我已經設法使所有東西都“起作用”，但是最后一個錯誤似乎沒有任何意義。 “術語'|'的表達式無效 在第15行。

Answer 1

如果您願意連接字符串，請使用

Color1 + "|" + Color2

因此，現在您的代碼應如下所示：

switch (Color1 + "|" + Color2)

另外，您將在第21行出現另一個錯誤，因為在Lblresult使用大寫字母“ L”而不是小寫字母“ l”

Answer 2

它顯示無效的表達式項切換類Program {static void Main（）{int Totalcoffeecost = 0; 字符串Userdecision = string.Empty; 做{int userchoice = -1; 做{

        Console.WriteLine("Please enter your coffee size: 1-small, 2-Medum,3-Large");
       userchoice = int.Parse(Console.ReadLine());
            }while(





     switch (userchoice)
        {
            case 1:
                Totalcoffeecost += 1;
                break;
            case 2:
                Totalcoffeecost += 2;
                break;
            case 3:
                Totalcoffeecost += 3;
                break;
            default:
                Console.WriteLine("Your choice {0} is invalid", userchoice);
                break;
        } 
        while(userchoice !=1 && userchoice !=2 && userchoice !=3)
            do
            {
                Console.WriteLine("Do you want to buy another coffee-Yes or No");
                string userdecision = "";
                userdecision = Console.ReadLine().ToUpper();
                if(userdecision != "Yes" && userdecision !="No")

                {
                    Console.WriteLine("your choice {0} is invalid. Please try again",userdecision);
                }
            }while(Userdecision != "Yes" && Userdecision != "No");
            }
        while(Userdecision.ToUpper()!="No");
        Console.WriteLine("Thank you for shopping with us");
        Console.WriteLine("Bill amount={0}",Totalcoffeecost );


        }
        }