Switch / Case

Switching on Values

Sometimes, you might have logic using conditional statements that ends up looking a bit cluttered, like the following first example. But, using a switch statement, you can make it much cleaner.

Cluttered if/else

This is a little cluttered, and requires reading the x variable several times.

if(x == 0)
        do_thing_a();
else if(x > 0 && x < 5)
        do_thing_b(x);
else if(x == 5)
        do_thing_c();
else if(x == 6)
        do_thing_d();
else do_thing_e();

Cleaner switch

This is cleaner, and only reads the x variable once.

switch(x)
{
        case 0:
                do_thing_a();
                break;
        case 0..5: // Value Range
                do_thing_b(x);
                break;
        case 5:
                do_thing_c();
                break;
        case 6:
                do_thing_d();
                break;
        default:
                do_thing_e();
                break;
}

Ex.: Percent Chance

Picking an outcome based on percentage chances easily using value ranges

switch(RandGen->Rand(99)) //0-99 inclusive
{
        case 0=..10:
                //10% chance
                break;
        case 10=..30:
                //20% chance
                break;
        case 30=..60:
                //30% chance
                break;
        case 60=..100:
                //40% chance
                break;
}

In a standard switch statement, each case : provided must include either a single compile-time constant value, which must match exactly, or a Value Range, in which case any value in the range will match.

If more than one case : would match, the first one from the top will match, and the rest won’t be checked. If NO case matches, the default: block will run (if provided).

break / fallthrough

The break statements are used to end the switch at the end of each case. If you do not include a break; at the end of a case, the code will fallthrough into the case below it. This can be desirable, but can also cause unexpected bugs if you aren’t looking out for it, as shown below:

switch(4)
{
        case 4:
                print("Read 4!\n");
        case 5:
                print("Read 5!\n");
}
/* Outputs:
Read 4!
Read 5!
*/

Switching on Strings

Additionally, switch statements can be used to compare entire strings! To do this, simply use string literals as the case : values!

char32[] str = "Test";
switch(str)
{
        case "Example":
                printf("Some Example Text\n");
                break;
        case "Test":
                printf("Testing Text!\n");
                break;
}
// Outputs: 'Testing Text!'

The STRING_SWITCH_CASE_INSENSITIVE option, if on, will make any of these switch statements it affects compare their values case-insensitively.

Not Yet Implemented

STRING_SWITCH_CASE_INSENSITIVE may become deprecated in favor of an annotation on switch statements instead.