Prestwood IT: Delphi Comparison Operators (=, <>) (Pascal and Delphi Coding)

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From the July 2009 Issue of Prestwood eMag

Delphi Language Details:

Delphi Comparison Operators (=, <>)

By Mike Prestwood

Posted 15 years ago on 1/16/2009

Delphi Code Snippet:

To/From Code Guide: Delphi Comparison Op... vs. Other Languages

A flashcard from our Delphi Flashcards Library

A code snippet from our Delphi Code Snippets Page

Tags: Delphi , Comparison Operators

KB101809

General Info: Round Floating Point Numbers

When comparing floating point numbers, make sure you round to an acceptable level of rounding for the type of application you are using.

Languages Focus: Comparison Operators

A comparison operator compares two values either literals as in "Hello" and 3 or variables as in X and Counter. Most languages use the same operators for comparing both numbers and strings. Perl, for example, uses separate sets of comparison operators for numbers and strings.

Delphi Comparison Operators

Common comparison operators:

=	equal
<>	not equal
<	less than
>	greater than
<=	less than or equal
>=	greater than or equal

Syntax Example:

//Does Delphi evaluate the math correctly? Yes!

//Refer to math.pas MaxSingle for more info.

if (0.1 + 0.1 + 0.1 = 0.3) then
  ShowMessage('correct')
else
  ShowMessage('not correct')

Delphi 2009 Working Example

Here's a simple working example from a button click event:

procedure TForm1.Button1Click(Sender: TObject);
var
  x: Boolean;
begin
  x := True;

  if x = True then
  begin
    ShowMessage('X was true');
  end
  else
  begin
    ShowMessage('X was false');
  end;
end;

More Info

Tip:	Round Floating Point Numbers

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Code Contributed By Mike Prestwood:

Mike Prestwood is a drummer, an author, and creator of the PrestwoodBoards online community. He is the President & CEO of Prestwood IT Solutions. Prestwood IT provides Coding, Website, and Computer Tech services. Mike has authored 6 computer books and over 1,200 articles. As a drummer, he maintains play-drums.com and has authored 3 drum books. If you have a project you wish to discuss with Mike, you can send him a private message through his PrestwoodBoards home page or call him 9AM to 4PM PST at 916-726-5675 x205.

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