18. Details on Generics collections tlist (9): binarysearch

Unit unit1;

Interface

Uses
Windows, messages, sysutils, variants, classes, graphics, controls, forms,
Dialogs, stdctrls;

Type
Tform1 = Class (tform)
Button1: tbutton;
Procedure button1click (Sender: tobject );
End;

VaR
Form1: tform1;

Implementation

{$ R *. DFM}

Uses generics. Collections, generics. defaults;

Procedure tform1.button1click (Sender: tobject );
VaR
List: tlist <string>;
Num: integer;
B: Boolean;
Comparer: icomparer;
Begin
List: = tlist <string>. Create ();
List. addrange (['123', 'abc', 'abc']);

{The default search must be exactly the same}
If list. binarysearch ('abc', num) Then showmessage (inttostr (Num); {2}

{Here is a custom comparator. If the first character matches, it will be found}
Comparer: = tcomparer <string>. Construct (
Function (const S1, S2: string): integer
Begin
Result: = ord (S1 [1])-ord (s2 [1]);
End );

If list. binarysearch ('abc', num, comparer) Then showmessage (inttostr (Num); {1}

List. Free;
End;

End.