GCop404.md

GCop 404

"Multiple if and else if on the same variable can be replaced with a 'switch'"

Rule description

Where multiple subsequent if conditions are checking the same variable against different values, prefer switch over if, because it is more readable and faster to run.

A switch has a semantic meaning. It's saying "pick one of these based on this variables value" (using a lookup table or a hash list for more than five items) but an if statement is just a series of boolean checks with no explicit semantic connection.

Example

if (foo == 0)
{
    ...
}
else if (foo == 1)
{
    ...
}
else if (foo == 2)
{
    ...
}

should be 🡻

switch (foo)
{
    case 0:
       ...
       break;
    
    case 1:
       ...
       break;
    
    case 2:
       ...
       break;
    
    default: 
       throw new NotSupportedException("...");
}