13

Does Delphi have an analog of enum in C?

Peter Mortensen
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Hacker
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    http://www.delphibasics.co.uk/Article.asp?Name=Sets – Tyzak Mar 04 '10 at 12:42
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    I don't know why everyone is linking to the DelphiBasics.co.uk site's article on enumerations, when the official documentation is available. Always prefer the official documentation: http://docwiki.embarcadero.com/RADStudio/Rio/en/Simple_Types_(Delphi)#Enumerated_Types – Andreas Rejbrand Jan 16 '20 at 11:07
  • @AndreasRejbrand I think this is because the official documentation was not accessible at the time. – Wolf Oct 08 '21 at 08:37
  • As a general note: Delphi always had better support for types, then C. – Gabriel Mar 10 '22 at 13:54

4 Answers4

46

Yes, Delphi has the following enumerated type construction:

type
  TDigits = (dgOne, dgTwo, dgThree <etc>);

Also, like in C, each symbol of an enumerated type may have a specified value, like this:

type
  TDigits = (dgOne = 1, dgTwo, dgThree <etc>);
da-soft
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    It should be added that the constants automatically get incremented (in relation to the direct predecessor) if there's no explicit value specified. – Wolf Oct 08 '21 at 08:34
9

Yes. Check out the first portion of Delphi Basics: Enumerations, SubRanges, and Sets.

Justin Niessner
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    I don't know why everyone is linking to the DelphiBasics.co.uk site's article on enumerations, when the official documentation is available. Always prefer the official documentation: http://docwiki.embarcadero.com/RADStudio/Rio/en/Simple_Types_(Delphi)#Enumerated_Types – Andreas Rejbrand Jan 16 '20 at 11:07
5

Have a look at

Enumerations, SubRanges and Sets

Adriaan Stander
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  • I don't know why everyone is linking to the DelphiBasics.co.uk site's article on enumerations, when the official documentation is available. Always prefer the official documentation: http://docwiki.embarcadero.com/RADStudio/Rio/en/Simple_Types_(Delphi)#Enumerated_Types – Andreas Rejbrand Jan 16 '20 at 11:07
1

In addition to the positive responses that are focused on the parallels, there are

Some restrictions:

1. Anonymous enumerations are not supported in Delphi.

So you have to translate

enum { SOME_CONSTANT = 42 };

into

const
  SOME_CONSTANT = 42

… which is, by the way, a better wording for your actual intent. But unfortunately, this can be translated back into something different. At least C++Builder 6 translates it like this in the auto-generated *.hpp file:

static const Shortint SOME_CONSTANT = 0x2A;

2. Explicit enum values were added with Delphi 6.

The feature of explicitly adding values to enumerators was introduced with Delphi 6. So you have to switch to normal constants, see this answer to How to create an enum with explicit values in Delphi 5 for more.

3. Finally, a restriction of C:

In C, enumerations are just compile-time constants that are implicitly converted into int as needed. This is basically where the support ends. Delphi has a stronger typing but provides information about the valid range and also iteration, see this snippet:

procedure TForm1.Button1Click(Sender: TObject);
type
  TMyEnum = (meOne, meTwo, meThree);
var
  v: TMyEnum;
  txt: String;
begin
  for v := Low(TMyEnum) to High(TMyEnum) do
    txt := txt + IntToStr(Integer(v)) + ' ';
  ShowMessage(txt)
end;
Wolf
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