Using INI Files

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INI Files

Basic Information

INI files can be used to save basic user settings easily. With the INIfiles unit and the TINIFile class you can easily work with existing INI files. This unit is found in the FCL.

INI Files

INI Files use brackets to create and mark Sections, which contain keys and key values. A Key and its corresponding Value are separated with an equals sign (Key=Value).

Section names are put inside square brackets ([Section]).

Comments are usually permitted and are marked with a semicolon (;) at the beginning of a line. As INI files are not totally standardized, other characters are also used, such as #

Nowadays, XML files are often used for string storage instead of INI files, because INI files don't handle large strings very well. However, ini(-like) files remain a dominant way of configuring Linux/Unix settings.

An example ini file:

; Comment. Beginning of INI file

; empty lines are ignored

; note that no section has been defined.
; Key: Compiler
; Value: Delphi

; This starts a General section
; Key Compiler and value FreePascal

Ini file reading example

The console application below shows how to read ini files. To test it one should create the following ini file with the name "C:\DB.ini". Edit it to so it contains a section called INIDB and the following keys and values:

; Save as C:\DB.ini

Now let's move on the the code..

Program IniSample;

{$mode objfpc}{$H+}



  // Create the object, specifying the place where it can find the ini file:
  INI := TINIFile.Create('C:\DB.ini');
  // Demonstrates reading strings from the INI file.
  // You can also read booleans etc.
  Author := INI.ReadString('INIDB','Author','');
  Pass := INI.ReadString('INIDB','Pass','');
  DBFile := INI.ReadString('INIDB','DBFile','');
  if Pass <> '' then
    Writeln('Password Required');
      if not (PassEnter = Pass) then Writeln('Wrong Password');
    until(PassEnter = Pass);
    Writeln('Correct Password');
  Writeln('Author : '+Author);
  Writeln('File : '+DBFile);
  Writeln('Password : '+Pass);
  // After we used ini file, we must call the Free method of object
  // ... although this really should be wrapped in a try..finally block
  // so that the object will be freed regardless of any errors above.

Objects to know

In the TINIFile class there are many different properties, procedures and functions that can be used.

CaseSensitive - This property allows you to say if the keys and sections are case sensitive or not. By default they aren't.

ReadString - Has 3 constant statements. The first one is the section to search in. The second one is the key to look for. The third one is a default string in case the key and/or section searched for is not found.

WriteString - has three constant statements, too. The first is the section. The second is the key and the last is the value that you want to write. If the key and section exist already, the key will be overwritten with the new value..

ReadSections - Will allow you to to take the sections from the INI file and put them in a TStrings class (or TStringList with the AS operator).

DeleteKey - Remove an existing key from a specific section.

EraseSection - Remove a section and all its data.

There are more procedures and functions but this is enough to get you started.

Reference Documentation

Here: Free Pascal documentation on INI files

See also