Delphi-PRAXiS - 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 </span right span style="color: rgb(0, 128, 0); font-weight: bold;"then/spanbr span style="color: rgb(0, 128, 0);"Result/span span style="color: rgb(102, 102, 102);":=/span span style="color: rgb(102, 102, 102);"-1/spanbr span style="color: rgb(0, 128, 0); font-weight: bold;"else/span span style="color: rgb(0, 128, 0); font-weight: bold;"if/span left span style="color: rgb(102, 102, 102);"> 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.

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