switch
suggest changeThe switch
statement is a control statement that selects a switch section to execute from a list of candidates. A switch statement includes one or more switch sections. Each switch section contains one or more case
labels followed by one or more statements. If no case label contains a matching value, control is transferred to the default
section, if there is one. Case fall-through is not supported in C#, strictly speaking. However, if 1 or more case
labels are empty, execution will follow the code of the next case
block which contains code. This allows grouping of multiple case
labels with the same implementation. In the following example, if month
equals 12, the code in case 2
will be executed since the case
labels 12
1
and 2
are grouped. If a case
block is not empty, a break
must be present before the next case
label, otherwise the compiler will flag an error.
int month = DateTime.Now.Month; // this is expected to be 1-12 for Jan-Dec
switch (month)
{
case 12:
case 1:
case 2:
Console.WriteLine("Winter");
break;
case 3:
case 4:
case 5:
Console.WriteLine("Spring");
break;
case 6:
case 7:
case 8:
Console.WriteLine("Summer");
break;
case 9:
case 10:
case 11:
Console.WriteLine("Autumn");
break;
default:
Console.WriteLine("Incorrect month index");
break;
}
A case
can only be labeled by a value known at compile time (e.g. 1
, "str"
, Enum.A
), so a variable
isn’t a valid case
label, but a const
or an Enum
value is (as well as any literal value).