Can you do a comparison with a case in a switch?

Projects Programming
1

How do you do comparison with a case within a switch?

   switch (i){
      case (i<3):   
             //Do something while i is less than 3
}

This doesn't Compile and I'm new... Unfortunately for me the Arduino Ref doesn't have an example. Which means you cannot do it or I'm doing it wrong. Any pointers appreciated.

2

No, you can't. The case argument must be a literal constant.

You can do...

   switch (i){
      case 1:   
      case 2:   
             //Do something while i is less than 3
             break;
      case 3:
      case 4:
      case 5:
             //Do something while i is 3 to 5
             break;
}

if that helps.

3 
case 0:
case 1:
case 2:
case 3:

// do same stuff for 0, 1, 2, 3

break;

is allowed.

4

Current implementations of the Arduio IDE are built around a version of GCC which allows this:

  int value = 3;
  switch ( value )
  {
    case 0 ... 3:
      break;
  }
5

Thank you Everyone. I really like lloyddean approach that is clean. Thanks again!

6

if things are complex you could create a function that returns an unique number for the different conditions.

simple example

int i = sign(strcmp(s1, s2));

switch(i)
{
  case -1: // s1 < s2 alphabetically
    break;
  case 0:  // s1==s2
    break;
  case 1:  // s1 > s2 alphabetically
}

Note that enums are allowed in a switch statement

enum Days {Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday};

Days d = f(...);

switch(s)
{
  case Saturday:
  case Sunday: 
    serial.println("Weekend");
    break;
  case Monday:
  case Tuesday:
  case Wednesday:
  case Thursday:
  case Friday:
    serial.println("Work days");
    break;
}