Group multiple cases together in the switch statement

Question

Here below is my code for a switch statement:

 switch(pin)
  {
  case 1:
    break;
  case 2:   case 3:  case 4:  case 5:  case 6:  case 7:  case 8:  case 9:  case 10:  case 11:
  case 12:  case 13:  case 14:  case 15:  case 16:  case 17:  case 18:  case 19:  case 20:
  case 21:  case 22:  case 23: case 24:case 25:case 26:case 27:case 28:case 29: case 30: case 31:
  case 32: case 33: case 34: case 35:

    dataOut[pin-2] = 1;
    DAQmxWriteDigitalLines(taskHandleOut,1,1,10.0,DAQmx_Val_GroupByChannel,dataOut,NULL,NULL);

    break;

  default:
    break;

In the above, the case 2-35 are to be grouped together for which, I mean, when pin is equal to 2-35, the specific task is to be performed.

I want to know if the above code is valid or not. I haven't seen case grouping in switch statements. Any weblinks for similar multiple case grouping is appreciated. Maybe there is some better way to do so instead of grouping multiple cases.

Answer 1

While your case may be better served with an if-check if (pin >= 2 && pin <= 35), it is common to group case labels like that.

gcc/clang/tinycc even have syntactic sugar for it:

switch(pin){
case 2 ... 35: /*nonstandard GNU extension; note well the whitespace*/
};

Answer 2

Yes, this is absolutely fine, although I'd write

if (pin >= 2 && pin <= 35){
    dataOut[pin-2] = 1;
    DAQmxWriteDigitalLines( ...
}

if I were you. If you are using gcc exclusively as your compiler, then you could also use case ranges.