Must be defined as 'a' 'b' as then they are of the type char, just a would be a variable name.
The values allowed in a switch statement behind the case include byte, char, int, long and unsigned versions of it. Furthermore the enum type can be used.
// sample code to show the usage of enum type
enum Days { Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday };
void setup()
{
Days thisDay = Sunday;
switch ( thisDay )
{
case Sunday:
break;
case Monday:
break;
case Tuesday:
break;
}
}
void loop()
{
}
[edit]enums are ideal for state machines[/edit]