Click here to Skip to main content
15,400,433 members
Articles / Desktop Programming / MFC
Posted 16 Sep 2002


95 bookmarked

How to read and write an INI File

Rate me:
Please Sign up or sign in to vote.
4.61/5 (35 votes)
17 Sep 20022 min read
List sections and section data (key-value pairs). Displays a key value and creates/modifies a key-value pair

Sample Image - INI.jpg


CIniReader is a class that reads/writes from/to an INI file.


Here are functions list of this class:

  • setINIFileName Sets the INI File name to read and write.
  • getKeyValue Used to retrieve a key value given the section and key name.
  • getSectionData Used to retrieve all key/value pairs of a given section.
  • getSectionNames Used to retrieve all the sections in an ini file
  • sectionExists Used to find out if a given section exists.
  • setKey Used to modify the key value or to create a key value pair for the specified section.

The functions in CIniReader use GetPrivateProfilexxx () functions to set, get information stored in an INI file. By having idea of the SDK functions like GetPrivateProfilexxx (), the functionality of the class can easily be extended.

Here is the CIniReader header file:

// CIniReader- Header File
class CIniReader  
  // method to set INI file name, if not already specified 
  void setINIFileName(CString strINIFile);
  // methods to return the lists of section data and section names
  CStringList* getSectionData(CString strSection);
  CStringList* getSectionNames();
  // check if the section exists in the file
  BOOL sectionExists(CString strSection);

  // updates the key value, if key already exists, 
  // else creates a key-value pair
  long setKey(CString strValue, CString strKey, CString strSection);

  // give the key value for the specified key of a section
  CString getKeyValue(CString strKey,CString strSection);
  // default constructor
    m_sectionList = new CStringList();
    m_sectionDataList = new CStringList();
  CIniReader(CString strFile)
    m_strFileName = strFile;
    m_sectionList = new CStringList();
    m_sectionDataList = new CStringList();
    delete m_sectionList;
    delete m_sectionDataList;
  // lists to keep sections and section data
  CStringList *m_sectionDataList;
  CStringList *m_sectionList;
  CString m_strSection;
  long m_lRetValue;
  // ini file name 
  CString m_strFileName;

How to use the class?

Demo project shows how to use the class. It takes from the user the fully qualified path and name of the INI file as C:\WINDOWS\ODBC.INI in the INI File name edit box. List Sections fills the list of sections in the INI file. Specifying any of the section names, and clicking the List Keys buttons will fill the second list box with the section data (all key and value pairs). Specifying a key name and pressing the Show Key Value button will display the value of the key. Update Key Value will update the modified value from the key value edit box for the key. If key not already present, update key value will create the specified key-value pair in the INI file. Be sure what you are doing, as it will modify the keys and values of INI.

Currently the buffer limit is up to 2000 characters, which can be increased according to the requirement.

After setting the INI file name just as the following code, you can proceed with using CIniReader functions:

// example of using the setINIFileName method
CIniReader  m_IniReader;
m_strINIFile = "C:\\WINDOWS\\ODBC.INI";
m_IniReader.setINIFileName (m_strINIFile); 
That's it. The class is so simple and easy to use, I am sure you will have no problem.


    This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

    A list of licenses authors might use can be found here


    About the Author

    Aisha Ikram
    Technical Lead
    United Kingdom United Kingdom
    I am currently working as a Technical Lead in UK. I worked in .NET 1.1/2.0, C#, VB.NET, ASP.NET, VC++ 6, MFC, ATL, COM/DCOM, SQL Server 2000/2005. These days i am learning all .Net 3.x stuff.

    Comments and Discussions

    QuestionThanks a lot! Pin
    3kboy2427-Jan-15 16:53
    Member3kboy2427-Jan-15 16:53 
    GeneralMy vote of 4 Pin
    VEMS20-Nov-12 6:51
    MemberVEMS20-Nov-12 6:51 
    GeneralGetPrivateprofileString fails while reading the value against certain sections if it is huge data against it. Pin
    deeps19859-May-11 2:37
    Memberdeeps19859-May-11 2:37 
    GeneralOptimization on enumeration functions :) Pin
    Behzad Ebrahimi6-Nov-10 3:46
    MemberBehzad Ebrahimi6-Nov-10 3:46 
    GeneralKey Count in INI file Pin
    April20048-Oct-10 18:52
    MemberApril20048-Oct-10 18:52 
    AnswerRe: Key Count in INI file Pin
    Behzad Ebrahimi6-Nov-10 3:37
    MemberBehzad Ebrahimi6-Nov-10 3:37 
    GeneralThanks Pin
    videoDev26-Aug-10 0:18
    MembervideoDev26-Aug-10 0:18 
    NewsTry this one too Pin
    GamePlanner20-Apr-09 11:16
    MemberGamePlanner20-Apr-09 11:16 
    GeneralRe: Try this one too Pin
    Behzad Ebrahimi6-Nov-10 3:50
    MemberBehzad Ebrahimi6-Nov-10 3:50 
    GeneralINI file Pin
    saiful_vonair14-Apr-09 16:01
    Membersaiful_vonair14-Apr-09 16:01 
    QuestionIs it possible to give the relative path of the ini file? Pin
    NILANKARAJA4-Dec-06 17:09
    MemberNILANKARAJA4-Dec-06 17:09 
    AnswerRe: Is it possible to give the relative path of the ini file? Pin
    mr0x27-Feb-07 21:55
    Membermr0x27-Feb-07 21:55 
    Generalthanks much Pin
    canercaner21-Oct-05 20:59
    Membercanercaner21-Oct-05 20:59 
    GeneralGood work Pin
    Adnan Shaheen Yousaf Zai25-Sep-05 22:01
    MemberAdnan Shaheen Yousaf Zai25-Sep-05 22:01 
    GeneralRe: Good work Pin
    Ejaz15-Oct-05 2:04
    MemberEjaz15-Oct-05 2:04 
    GeneralRe: Good work Pin
    Behzad Ebrahimi6-Nov-10 3:40
    MemberBehzad Ebrahimi6-Nov-10 3:40 
    GeneralRe: Good work Pin
    Ejaz15-Nov-10 17:18
    MemberEjaz15-Nov-10 17:18 
    QuestionRemove a key? Pin
    momo727-Jun-05 22:18
    Membermomo727-Jun-05 22:18 
    AnswerRe: Remove a key? Pin
    Lee Sung Ho20-Mar-06 22:20
    MemberLee Sung Ho20-Mar-06 22:20 
    GeneralGood Article Pin
    Thiagarajan Rajendran4-Nov-04 19:02
    MemberThiagarajan Rajendran4-Nov-04 19:02 
    GeneralError message from linker Pin
    walter1234566-Apr-03 2:02
    Memberwalter1234566-Apr-03 2:02 
    GeneralRe: Error message from linker Pin
    Aisha Ikram6-Apr-03 20:27
    MemberAisha Ikram6-Apr-03 20:27 
    GeneralYou can use my class in your C++/Win32/MFC code Pin
    Aisha Ikram16-Mar-03 22:17
    MemberAisha Ikram16-Mar-03 22:17 
    GeneralRe: You can use my class in your C++/Win32/MFC code Pin
    Kin Hoon17-Aug-03 7:40
    MemberKin Hoon17-Aug-03 7:40 
    GeneralRequest to Author Pin
    Tom diep22-Jan-03 15:56
    sussTom diep22-Jan-03 15:56 

    General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

    Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.