Stuff at the beginning of a new program?

[undermanager]

When I start a new program, I get a lot of 'stuff' apearing (see below). I usually delete this from my Pascal programs, and everything always works fine. Why is it there if it doesn't affect my programs? What (Non-techy explanation) is this code doing? I have searched for a simple explanation of what all this is but can't find anything below Einstein level.

Thanks.


program project1;

{$mode objfpc}{$H+}

uses


  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  Classes
  { you can add units after this };
{$R *.res}   

[Blaazen]

{$mode} are Pascal dialects. There can be Delphi or TP (TurboPascal) for better compatibility. Keep the objpas, it's the best.
{$H+} is type of strings. Keep it. http://www.freepascal.org/docs-html/prog/progsu23.html#x29-280001.1.23

This stuff
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}

is important if you are planning to use Threads in unix/linux (or in a multiplatform application).

[Leledumbo]

I have searched for a simple explanation of what all this is but can't find anything below Einstein level.

Does this and this sound Einstein to you?

[undermanager]

Thanks Blaazan.

Can you tell me how to use a Pascal library like Crt or sysutils, please. I get an error with hte following, although if I comment out the stuff above Crt, it all works fine:

program project1;

{$mode objfpc}{$H+}

uses

  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  Classes
  { you can add units after this };

  Crt;


{$R *.res}

begin
  writeln('Hello world');
  readln();

end.

{$mode} are Pascal dialects. There can be Delphi or TP (TurboPascal) for better compatibility. Keep the objpas, it's the best.
{$H+} is type of strings. Keep it. http://www.freepascal.org/docs-html/prog/progsu23.html#x29-280001.1.23

This stuff
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}

is important if you are planning to use Threads in unix/linux (or in a multiplatform application).

[typo]

Code: [Select]

program project1;

{$mode objfpc}{$H+}

uses

  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  Classes,
  Crt, SysUtils
  { you can add units after this };

{$R *.res}

begin
  writeln('Hello world');
  readln();
end.


[undermanager]

Thanks. I'm never going to get the hang of when to use / not use commas and semicolons in Lazarus!!

 

[howardpc]

The Pascal rule is straightforward: every Pascal statement has to end in a semicolon, thus:
Pascal statement 1;
Pascal statement 2;
Pascal statement 3;

This means it is simple for the compiler to parse the source, which is one reason Pascal compilers are fast.

Commas are mostly used to separate items within a Pascal statement, so in a uses statement

Code: [Select]

uses Classes;
does not need a comma (only one item in the list),

whereas the statements:

Code: [Select]

uses Classes, Dialogs;


Code: [Select]

uses Classes, Dialogs, SysUtils;
do need commas, since there is more than one item in the list.

[Leledumbo]

The Pascal rule is straightforward: every Pascal statement has to end in a semicolon

Correction: Pascal statements are separated rather than terminated by semicolon. The semicolon is read as "and then" in English.