Is It Possible To Do The Following In A Switch Statement - C++?

Question

Hi there,

I am a programming student in my second OOP class, and I have a simple question that I have not been able to find the answer to on the internet, if it's out there, I apologize.

My question is this:

Is it possible have Boolean conditions in switch statements?

Example:

switch(userInputtedInt)
{
    case >= someNum && <= someOtherNum
    break;
    // Is this possible?
}

Answer 1

No this is not possible in C++. Switch statements only support simple integer matches. If you need a complex boolean condition then you should use an if / else block

Answer 2

/////////////// Nope

Answer 3

This isn't possible. The closest you can some, if the values are reasonably close together is

switch(userInputtedInt)
{
    case someNum:
    case someNum+1:
    // ... 
    case someOtherNum:
    break;

}

Answer 4

C++ does not support that.

However, if you are not concerned with writing portable, standard code some compilers support this extended syntax:

switch(userInputtedInt)
{
    case someNum...someOtherNum:
    break;
}

Those values must be constant.

Answer 5

No, this is usually the purview of the if statement:

if ((userInputtedInt >= someNum) && (userInputtedInt <= someOtherNum)) { ... }

Of course, you can incorporate that into a switch statement:

switch (x) {
    case 1:
        // handle 1
        break;
    default:
        if ((x >= 2) && (x <= 20)) { ... }
}

Answer 6

It's not possible directly -- a C or C++ switch statement requires that each case is a constant, not a Boolean expression. If you have evenly distributed ranges, you can often get the same effect using integer division though. e.g. if you have inputs from 1 to 100, and want to work with 90-100 as one group, 80-89 as another group, and so on, you can divide your input by 10, and each result will represent a range.

Answer 7

As others have said you can't implement this directly as you are trying to do because C++ syntax doesn't allow it. But you can do this:

switch( userInputtedInt )
{
  // case 0-3 inclusve
  case 0 :
  case 1 :
  case 2 :
  case 3 :
    // do something for cases 0, 1, 2 & 3
    break;

  case 4 :
  case 5 :
    // do something for cases 4 & 5
    break;
}

Answer 8

No. And trying it is the best way to learn.

Answer 9

If you fancy the preprocessor you could write some kind of macro that auto-expands to the number of case statement required. However that would require a lengthly file with pretty much all case statements (ex: #define CASE0 case 0: #define CASE1 case 1: ...)

You shouldn't go there but it's fun to do...for fun! ;)