为什么我的 {$IFDEF DEBUG} 条件在 Delphi 中不起作用？

Question

I have the following code (IP addresses changed) in a Delphi 7 project.

const
{$IFNDEF DEBUG}
    AUTHENTICATOR_DB_ADMIN_HOST = '123.456.789.12';
{$ELSE}
    AUTHENTICATOR_DB_ADMIN_HOST = '127.0.0.1';
{$ENDIF}

Under project options:

• In the "Directories/Conditionals" tab under the section marked "Conditionals", I have a single definition: "DEBUG".
• In the "Version Info" tab under the section marked "Module Attributes", I have ticked the checkbox labelled "Debug-build".

In the above code example, the "DEBUG" symbol is not defined, so the IP address is set to 123.456.789.12 instead of 127.0.0.1 . What am I doing wrong?

This question is following on from Does Delphi's conditional compilation allow the defined symbols to contain values?

Answer 1

If you compile your project and there are no changes and the DCU is available on the path for the last non debug build then it will be used, causing this problem. Also make sure this unit is included in the uses clause of the DPR.

If you build the project it will force a recompile of all units added to the project.

I generally compile for syntax but always build for testing/deployment.

Answer 2

Old question I know, but here is the answer for me. In Delphi 2010 (an no doubt others) the DEBUG condition is set by the Configuration Manager, it's a Reserved Word as it were.

Consider this trivial example: -

program Buggy;

{$APPTYPE CONSOLE}

uses
  SysUtils;

begin
{$IFDEF DEBUG}
  WriteLn('DEBUG condition is ON.');
{$ELSE}
  WriteLn('DEBUG condition is OFF.');
{$ENDIF}
{$IFDEF RELEASE}
  WriteLn('RELEASE condition is ON.');
{$ELSE}
  WriteLn('RELEASE condition is OFF.');
{$ENDIF}
  ReadLn;
end.

You can change the setting of these conditions by changing the compiler configuration: -

In short, don't use DEBUG or RELEASE for your own use - make up a unique directive for your testing.

Despite other comments I use conditions which helps with syntax errors, smaller exe's and prevents reverse engineering of code I don't want released.

Answer 3

“$IFNDEF”代替“IFDEF”（否定形式Ndef代替def）。