Using the StartsWith function in a Switch Case Statement

I have a quick question that I cant find an answer to:

How come I can say (importing the system namespace of course):

if(someString.StartsWith("bla")){
     do something...
}

but I can’t say:

switch(someString.StartsWith){
     case "bla":
         do this...
     case "idk":
         do that...
}

Thanks.

someString.StartsWith("whatever") returns a bool, not a string! You can't use it like that. If you're trying to get the first 3 characters of the string, you would use

switch(someString.SubString(0, 3))
{
    case "bla":
        do some things...
    case "idk":
        do something else...
}

This is compatible with using a switch in this way, because it returns a string which can then be compared in your cases!