Using the where keyword

We use the where keyword to add additional tests within the case statement:

switch a 
{ 
  case 0..<10 where a%2 == 0: 
    print("a is a single digit positive even number") 
  case 0..<10: 
    print("a is a single digit positive odd number") 
  default: 
    print("a is not a single digit positive number") 
}