Delphi Basics : $LongStrings command

DelphiBasics

$LongStrings
Compiler Directive

Treat string types as AnsiString or ShortString

{$LongStrings Off}

1
2	{$LongStrings On}

Description

The $LongStrings compiler directive determines whether Delphi treats the string type as an AnsiString when on (default) or ShortString when off.

The default recognises that the general use of string types is to hold data that is likely to be longer than 255 characters (ShortString capacity).

Notes

$LongStrings is equivalent to $H.

$LongStrings can be used multiple times in your code, but this is not recommended (except for illustration purposes in the example).

The default value is $LongStrings On

Related commands

$H		Treat string types as AnsiString or ShortString
AnsiString		A data type that holds a string of AnsiChars
ShortString		Defines a string of up to 255 characters
String		A data type that holds a string of characters

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Example code : Packing a record to reduce storage

var
  // Define littleString to be treated as a ShortString
  {$LongStrings Off}
  littleString : string;

  // Define bigString to be treated as an AnsiString
  {$LongStrings On}
  bigString : string;
begin
  // Show the size of the little string - 256 bytes
  ShowMessageFmt('littleString size = %d',[SizeOf(littleString)]);

  // Show the size of the big string - 4 - a pointer to text
  ShowMessageFmt('   bigString size = %d',[SizeOf(bigString)]);
end;

Show full unit code

littleString size = 256
bigString size = 4