UnicodeSupport topic

In unit System

Unicode and codepage support.

Declaration

pascal

UnicodeSupport

Description

The system unit works with Short-, Ansi-, and UnicodeString routines for all string related operations.

Ansistrings are code-page aware, which means that code page information is associated with them. For most routines, the support for converting these code pages is natural. For some routines, care must be taken when converting from codepage-aware strings to widestring.

The codepage conversion support is influenced by the following variables:

Name	Description
DefaultSystemCodePage	Actual code page to use when CP_ACP is encountered
DefaultUnicodeCodePage	Code page for new Unicode strings
DefaultFileSystemCodePage	Codepage to use when sending strings to single-byte OS file system routines.
DefaultRTLFileSystemCodePage	Codepage to use when receiving strings from single-byte OS file system routines.

The windows code page identifiers are used. There are 3 special codepage identifiers:

Name	Description
CP_ACP	Currently set default system codepage
CP_OEMCP	OEM (console) code page (only on windows)
CP_NONE	Indicates absence of code page information for a string
DefaultRTLFileSystemCodePage

The following routines may perform code page conversions:

Name	Description
LowerCase	Return lowercase version of a string.
UpCase	Convert a string to all uppercase.
GetDir	Return the current directory.
MkDir	Create a new directory.
ChDir	Change current working directory.
RmDir	Remove directory when empty.
Assign	Assign a name to a file.
Erase	Delete a file from disk.
Rename	Rename file on disk.
Read	Read from a text file into variable.
ReadLn	Read from a text file into variable and goto next line.
Write	Write variable to a text file or standard output.
WriteLn	Write variable to a text file or standard output and append newline.
ReadStr	Read variables from a string.
WriteStr	Write variables to a string.
Insert	Insert one string or dynamic array in another.
Copy	Copy part of a string or dynamic array.
Delete	Delete elements (characters) from a string or dynamic array.
`SetString`

All these routines exist also in Unicode versions.

Note that for conversion of codepages and Unicode strings, a Unicode manager must be present. On windows, the system is used for this. On Unix, one of the fpwidestring or cwstring units must be used.

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.