C# Switch EnumUse switch on enum variables. Add cases with enum values, which are constants and can be matched in switch.
Switch enum. In C# switch can act upon enum values. An enum switch sometimes results in clearer code. The resulting instructions are sometimes faster as well.
A common pattern. The C# switch-enum code pattern is often effective. It is used in many real-world programs (not just website examples).
Example. Enums help us deal with magic constants. For the switch statement here, look at the IsImportant method—it uses 5 explicit cases and a default case.
using System;
enum Priority
{
Zero,
Low,
Medium,
Important,
Critical
};
class Program
{
static void Main()
{
// New local variable of the Priority enum type.
Priority priority = Priority.Zero;
// Set priority to critical on Monday.
if (DateTime.Today.DayOfWeek == DayOfWeek.Monday)
{
priority = Priority.Critical;
}
// Write this if the priority is important.
if (IsImportant(priority))
{
Console.WriteLine("The problem is important.");
}
// See if Low priority is important.
priority = Priority.Low;
Console.WriteLine(IsImportant(priority));
// See if Important priority is.
priority = Priority.Important;
Console.WriteLine(IsImportant(priority));
}
static bool IsImportant(Priority priority)
{
// Switch on the Priority enum.switch (priority)
{
case Priority.Low:
case Priority.Medium:
case Priority.Zero:
default:
return false;
case Priority.Important:
case Priority.Critical:
return true;
}
}
}The problem is important.
False
True
Internals. How is the enum switch compiled? The C# code is compiled into a special .NET instruction called a jump table. The jump table uses the IL instruction switch.
A summary. We saw examples of how you can switch on enums. Switch can improve performance when it is implemented by a jump table in the MSIL. This is determined by the compiler.
