Friday, May 15, 2020
How to Manipulate INI files from Delphi
INI files are text-based files used for storing an applications configuration data. Even though Windows recommends using the Windows Registry to store application-specific configuration data, in many cases, youll find that INI files provide a quicker way for the program to access its settings. Windows itself even uses INI files; desktop.ini and boot.ini being just two examples. One simple use of INI files as a status saving mechanism would be to save the size and location of a form if you want a form to reappear at its previous position. Instead of searching through a whole database of information to find the size or location, an INI file is used instead. The INI File Format Initialization or Configuration Settings file (.INI) is a text file with a 64 KB limit divided into sections, each containing zero or more keys. Each key contains zero or more values. Heres an example: [SectionName] keyname1value ;comment keyname2value Section names are enclosed in square brackets and must begin at the beginning of a line. Section and key names are case-insensitive (the case doesnt matter), and cannot contain spacing characters. The key name is followed by an equal sign (), optionally surrounded by spacing characters, which are ignored. If the same section appears more than once in the same file, or if the same key appears more than once in the same section, then the last occurrence prevails. A key can contain string, integer, or boolean value.​ Delphi IDE uses the INI file format in many cases. For example, .DSK files (desktop settings) utilize the INI format. TIniFile Class Delphi provides the TIniFile class, declared in the inifiles.pas unit, with methods to store and retrieve values from INI files. Prior to working with the TIniFile methods, you need to create an instance of the class: uses inifiles; ... var   IniFile : TIniFile; begin   IniFile : TIniFile.Create(myapp.ini) ; The above code creates an IniFile object and assigns myapp.ini to the only property of the class  the FileName property  used to specify the name of the INI file you are to use. The code as written above looks for the myapp.ini file in the \Windows directory. A better way to store application data is in the applications folder - just specify the full pathname of the file for the Create method: // place the INI in the application folder, // let it have the application name // and ini for extension: iniFile : TIniFile.Create(ChangeFileExt(Application.ExeName,.ini)) ; Reading From INI The TIniFile class has several read methods. The ReadString reads a string value from a key, ReadInteger. ReadFloat and similar are used to read a number from a key. All read methods have a default value that can be used if the entry does not exist. For example, the ReadString is declared as: function ReadString(const Section, Ident, Default: String): String; override; Write to INI The TIniFile has a corresponding write method for each read method. They are WriteString, WriteBool, WriteInteger, etc. For example, if we want a program to remember the name of the last person who used it, when it was, and what the main form coordinates were, we might establish a section called Users, a keyword called Last, Date to track the information, and a section called Placement with keys Top, Left, Width, and Height. project1.ini  [User]  LastZarko Gajic  Date01/29/2009  [Placement]  Top20  Left35  Width500  Height340 Note that the key named Last holds a string value, Date holds a TDateTime value, and all keys in the Placement section hold an integer value. The OnCreate event of the main form is the perfect place to store the code needed to access the values in the applications initialization file: procedure TMainForm.FormCreate(Sender: TObject) ; var   appINI : TIniFile;   LastUser : string;   LastDate : TDateTime; begin   appINI : TIniFile.Create(ChangeFileExt(Application.ExeName,.ini)) ;   try     //if no last user return an empty string     LastUser : appINI.ReadString(User,Last,) ;     //if no last date return todays date     LastDate : appINI.ReadDate(User, Date, Date) ;     //show the message     ShowMessage(This program was previously used by LastUser on DateToStr(LastDate));     Top : appINI.ReadInteger(Placement,Top, Top) ;     Left : appINI.ReadInteger(Placement,Left, Left);     Width : appINI.ReadInteger(Placement,Width, Width);     Height : appINI.ReadInteger(Placement,Height, Height);   finally     appINI.Free;   end; end; The main forms OnClose event is ideal for the Save INI part of the project. procedure TMainForm.FormClose(Sender: TObject; var Action: TCloseAction) ; var   appINI : TIniFile; begin   appINI : TIniFile.Create(ChangeFileExt(Application.ExeName,.ini)) ; try     appINI.WriteString(User,Last,Zarko Gajic) ;     appINI.WriteDate(User, Date, Date) ;     with appINI, MainForm do     begin       WriteInteger(Placement,Top, Top) ;       WriteInteger(Placement,Left, Left) ;       WriteInteger(Placement,Width, Width) ;       WriteInteger(Placement,Height, Height) ;     end;   finally     appIni.Free;   end; end; INI Sections The EraseSection erases an entire section of an INI file. ReadSection and ReadSections fill a TStringList object with the names of all sections (and key names) in the INI file. INI Limitations Downsides The TIniFile class uses the Windows API which imposes a limit of 64 KB on INI files. If you need to store more than 64 KB of data, you should use the TMemIniFile. Another problem might arise if you have a section with more than 8 K value. One way to solve the problem is to write your own version of the ReadSection method.
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