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In - used to test if a value is a member of a set

Ordinal expression in Set expression Description The In keyword tests whether a value is in a set. It returns true if it is, false if not. Notes Sets are limited to 256 different values. Each element is equated with the Integer values 0,1,2 ... 255 Integer sets map directly to these element values, and are therefore limited to a high value of 255. However, you may compare a value greater than 255 with an Integer set. Delphi simply uses the lowest byte of the Integer. For example, a test value of 258 would have a lower byte value of 3. Related commands Exclude Exclude a value in a set variable Include Include a value in a set variable Set Defines a set of up to 255 distinct values Example code : Determine whether a character is a letter begin IsLetter('G'); // G is a letter of the (uppercase) alphabet IsLetter('1'); // 1 is not a letter end; // Test if a character is a letter procedure TForm1.IsLetter(Letter : char); var Alphabet : set of 'A'..'Z'; begin Alphabet := ['A'..'Z']; if Letter In Alphabet then ShowMessage(Letter+' is in the alphabet') else ShowMessage(Letter+' is NOT in the alphabet'); end; Show full unit code G is in the alphabet 1 is NOT in the alphabet