[英]Return a file location from a switch-statement
我对编程很陌生,但我试图让我的方法返回一个值,该值包含依赖于用户所需选择的文件位置。 我已经为此摆弄了一天多,并且坚持如何正确返回值,我一直告诉我并非所有代码路径都返回值。 如何解决此问题并将代码路径返回到主
public static string fileLocation()
{
int fileRequest = 10;
bool errorCheck = true;
string filePath;
while (errorCheck == true)
{
Console.Write(">Enter '1' through '9' to choose a hand.");
Console.Write("Enter '0' for random.");
fileRequest = Convert.ToInt16(Console.ReadLine());
switch (fileRequest)
{
case 0:
Console.WriteLine(">Random selection loading.");
Random rnd = new Random();
fileRequest = rnd.Next(10);
errorCheck = true;
return (null);
case 1:
Console.WriteLine(">Loading file one.");
filePath = Path.GetFullPath("Flush.txt");
errorCheck = false;
return (Convert.ToString(filePath));
case 2:
Console.WriteLine(">Loading file two.");
filePath = Path.GetFullPath("FourKind.txt");
errorCheck = false;
return (Convert.ToString(filePath));
case 3:
Console.WriteLine(">Loading file three.");
filePath = Path.GetFullPath("FullHouse.txt");
errorCheck = false;
return (Convert.ToString(filePath));
case 4:
Console.WriteLine(">Loading file four.");
filePath = Path.GetFullPath("Pair.txt");
errorCheck = false;
return (Convert.ToString(filePath));
case 5:
Console.WriteLine(">Loading file five.");
filePath = Path.GetFullPath("RoyalFlush.txt");
errorCheck = false;
return (Convert.ToString(filePath));
case 6:
Console.WriteLine(">Loading file six.");
filePath = Path.GetFullPath("Straight.txt");
errorCheck = false;
return (Convert.ToString(filePath));
case 7:
Console.WriteLine(">Loading file seven.");
filePath = Path.GetFullPath("StraightFlush.txt");
errorCheck = false;
return (Convert.ToString(filePath));
case 8:
Console.WriteLine(">Loading file eight.");
filePath = Path.GetFullPath("ThreeKind.txt");
errorCheck = false;
return (Convert.ToString(filePath));
case 9:
Console.WriteLine(">Loading file nine.");
filePath = Path.GetFullPath("TwoPair.txt");
errorCheck = false;
return (Convert.ToString(filePath));
default:
Console.WriteLine(">Invalid request.");
filePath = "Invalid";
errorCheck = true;
return (null);
}
}
我假设您要做的是将 0 到 9 之间的整数作为输入。 如果是0,你想把它随机当作1到9。如果是别的,你想再次要求输入。 这应该这样做(未经测试):
public static string FileLocation()
{
while (true)
{
Console.Write(">Enter '1' through '9' to choose a hand.");
Console.Write("Enter '0' for random.");
int fileRequest = Convert.ToInt16(Console.ReadLine());
if (fileRequest == 0)
fileRequest = (new Random()).Next(1, 10);
switch (fileRequest)
{
case 1:
Console.WriteLine(">Loading file one.");
return Path.GetFullPath("Flush.txt");
case 2:
Console.WriteLine(">Loading file two.");
return Path.GetFullPath("FourKind.txt");
case 3:
Console.WriteLine(">Loading file three.");
return Path.GetFullPath("FullHouse.txt");
case 4:
Console.WriteLine(">Loading file four.");
return Path.GetFullPath("Pair.txt");
case 5:
Console.WriteLine(">Loading file five.");
return Path.GetFullPath("RoyalFlush.txt");
case 6:
Console.WriteLine(">Loading file six.");
return Path.GetFullPath("Straight.txt");
case 7:
Console.WriteLine(">Loading file seven.");
return Path.GetFullPath("StraightFlush.txt");
case 8:
Console.WriteLine(">Loading file eight.");
return Path.GetFullPath("ThreeKind.txt");
case 9:
Console.WriteLine(">Loading file nine.");
return Path.GetFullPath("TwoPair.txt");
default:
Console.WriteLine("Invalid request.");
break;
}
}
}
好吧,您遇到了编译器无法理解的情况。
您正在 while 循环中检查 errorCheck 并且内部有一个案例。 这种情况总是会返回,但是当编译器看到 errorCheck 在没有返回的情况下为真的可能性时,它会抱怨执行路径不存在返回的可能性。
首先,您在所有情况下都在执行 return,因此可以安全地删除 while,因为它什么都不做。 否则,如果您计划始终返回并始终循环,直到用户选择正确的选项忽略ERRORCHECK,只需执行一段时间(true){...},因为在选择正确的选项时,您的交换机将返回。
一个用 VB 编写的示例,但它应该显示逻辑。 我的变量来自在 OnLoad 事件中填充的数据库变量,但除此之外,它几乎就是您要执行的操作。
Private Sub ShowPDF()
Dim mySelection As Integer = _myDb.MyHuntingArea
'the path where the pdf files are located
Dim filePath As String = MyMachine.AssemblyDirectory & "\Regulations\"
'variable for the appropriate file name to get
Dim fileName As String = ""
Select Case mySelection
Case 1
fileName = filePath & "Area1.pdf"
Case 2
fileName = filePath & "Area2.pdf"
Case 3
fileName = filePath & "Area3.pdf"
Case Else
MessageBox.Show("We cannot determine what area you are requesting regulations for. Make sure it is set under Setup.", Application.ProductName, MessageBoxButtons.OK, MessageBoxIcon.Error)
End Select
If Not fileName = "" Then
Try
System.Diagnostics.Process.Start(fileName)
Catch ex As Exception
MsgBox(ex.Message)
End Try
End If
End Sub
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