C# Switch-case 字符串以

Question

Is there any way to make a case condition in a switch statement where you say if a string end with something?

switch (Pac.Sku)
{
    case "A":
        pacVM.Sucursal = "Managua";
        break;
    case "B":
        pacVM.Sucursal = "Masaya";
        break;
    case "C":
        pacVM.Sucursal = "Leon";
        break;
    default:
        pacVM.Sucursal = "N/A";
        break;
}

Answer 1

Get the last character of the string, and switch over the result:

switch (Pac.Sku.Last())
{
    case 'A':
        pacVM.Sucursal = "Managua";
        break;

    case 'B':
        pacVM.Sucursal = "Masaya";
        break;

    case 'C':
        pacVM.Sucursal = "Leon";
        break;

    default:
        pacVM.Sucursal = "N/A";
        break;
}

If the string could be null or empty use something like this function instead of Last() . This function returns null if the string is null , null if the string is empty, and the last character of the string if it is not null or empty:

char? GetLast(string s)
{
    return s?.Length > 0 ? s.Last() : (char?)null;
}

Switch:

switch(GetLast(Pac.Sku))

Answer 2

You can usepattern matching feature of C# 7.0 to achieve this. Here is a very basic example:

var t = "blah";

switch (t)
{
    case var a when t.EndsWith("bl"):
        Console.WriteLine("I'm not here");
        break;

    case var b when t.EndsWith("ah"):
        Console.WriteLine("I'm here");
        break;
}

Answer 3

You can get creative with a Func<string, string>[] like this:

Func<string, string>[] cases = new Func<string, string>[]
{
    x => x.EndsWith("A") ? "Managua" : null,
    x => x.EndsWith("B") ? "Masaya" : null,
    x => x.EndsWith("C") ? "Leon" : null,
    x => "N/A",
};

Func<string, string> @switch = cases.Aggregate((x, y) => z => x(z) ?? y(z));

string result = @switch(Pac.Sku);

I have tested this with sample input that matches each of the cases and it works just fine.

One significant advantage with this approach is that you can build the Func<string, string>[] at run-time. Nice for creating configurable solutions.

You're also not limited to just using EndsWith - any condition can be used that suits the purpose.

Answer 4

I think it's not a way! You can only use the if-else

if (Pac.Sku.EndsWith("A") )
{
    pacVM.Sucursal= "Managua";
}
else if (Pac.Sku.EndsWith("B"))
{
    pacVM.Sucursal= "Masaya";
}
else if (Pac.Sku.EndsWith("C"))
{
    pacVM.Sucursal= "Leon";
}
else
{
    pacVM.Sucursal= "N/A";
}