CompareValue for booleans

CompareValue function is incredibly practical when you are writing comparers (functions that determine how some data structure is ordered). System.Math and System.StrUtils define a bunch of functions that can be used to compare integers, doubles, strings … There’s, however, no CompareValue for booleans.

A CompareValue function compares two parameters, traditionally named left and right, and returns 0 if they are the same, –1 if left is smaller and 1 if right is smaller.

If we use the usual ordering of false < true, we can write the missing function as follows:

function CompareValue(left, right: boolean): integer; overload;
begin
  if left < right then
    Result := -1
  else if left > right then
    Result := 1
  else
    Result := 0;
end;

Your task for today – if you choose to accept it – is: Write this function without any if statements.

Visit “What’s new in Rio 10.3.2” in Ljubljana

On September 26^th I’ll talk about RAD Studio Rio in Ljubljana. We’ll discuss 10.3 a bit and 10.3.1/10.3.2 updates in more detail. We’ll also look into the future to see what 10.4 might bring.

This will also be a good opportunity to see my latest book, Design patterns with Delphi, or get your own copy signed.

Participation is free, but you should register here so we can prepare enough food for everyone.