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A Simple Class to Read and Write INI Files

, 30 Nov 2006 CPOL
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This class is a thin MFC wrapper around Win32 API for reading/writing INI files.


This is a further exploration if the INI file class theme started by Xiangxiong Jian (xiaohe521) and Adam (aejw) on The Code Project. The main idea remains pretty much the same: the class is a thin wrapper around Win32 API for reading/writing INI files. However, I was trying to gear my class more towards the MFC.

This class may be useful if your application needs to access both registry and INI file, or multiple INI files. Otherwise, you could use AfxGetApp()->m_pszProfileName and AfxGetApp()->GetProfileXXXX(…).

Class Declaration

class CIniFile : public CObject
 CIniFile(LPCTSTR lpIniFileName, INT iMaxStringLength);
 virtual ~CIniFile();
// Attributes
 CString  m_strFileName; 	// path to the INI file
 const INT m_MAXSTRLEN; 	// max length of a string (excluding the key name)
                        	//that can be written/read to/from the
                        	// INI file by this instance
// Operations
 CString GetIniFileName();
 void SetIniFileName(LPCTSTR lpIniFileName);
 BOOL GetStatus(CFileStatus& rStatus);
void GetString(LPCTSTR lpSection, LPCTSTR lpKey,
       CString& strRet, LPCTSTR strDefault);
UINT GetInt(LPCTSTR lpSection, LPCTSTR lpKey, INT iDefaultValue);
FLOAT GetFloat(LPCTSTR lpSection, LPCTSTR lpKey, FLOAT fDefaultValue);
BOOL GetStruct(LPCTSTR lpSection, LPCTSTR lpKey,
       LPVOID lpRetStruct, UINT iSizeStruct);
void GetSectionNames(CStringList& lstSectionNames);
BOOL WriteSection(LPCTSTR lpSection, LPCTSTR lpData);
BOOL WriteString(LPCTSTR lpSection, LPCTSTR lpKey, LPCTSTR lpString);
BOOL WriteNumber(LPCTSTR lpSection, LPCTSTR lpKey, INT iValue);
BOOL WriteNumber(LPCTSTR lpSection, LPCTSTR lpKey, FLOAT fValue);
BOOL WriteStruct(LPCTSTR lpSection, LPCTSTR lpKey,
       LPVOID lpStruct, UINT iSizeStruct);
 BOOL RemoveKey(LPCTSTR lpSection, LPCTSTR lpKey); 

Class Implementation

The implementation is very straightforward. It’s based on the following API functions:

  • GetPrivateProfileSectionNames
  • GetPrivateProfileStruct
  • GetPrivateProfileString
  • GetPrivateProfileInt
  • WritePrivateProfileStruct
  • WritePrivateProfileString
  • WritePrivateProfileSection

Download the source code for details (it's fairly well commented).

Demo Application / Test Bed

Here’s the console application that exercises the methods of the class. The output goes to the afxDump.

// just a dummy structure to write/read to/from the INI file
struct TestStruct : public POINT
 char charr[8];
// PURPOSE: test bed for the INI file class
void TestIniClass()
 CIniFile iniFile(".\\test1.ini", 1024);
 iniFile.SetIniFileName(".\\test2.ini");     		// change the file name 
					 // after the class has bee created
// test the writing to the INI file
iniFile.WriteSection("section1", "key1=test1\x000key2=test2"); // make a section
                           // with 2 new keys
iniFile.WriteSection("section2", "key1=test1");    // make another section
iniFile.WriteString("section1", "key3", "test3");    // create a new key
iniFile.WriteString("section1", "key2", "test4");    // update an existing key
iniFile.WriteString("section1", "key1", NULL);     // remove an existing key
iniFile.RemoveKey("section1", "key3");             // remove another existing key
iniFile.WriteNumber("section1", "key4", 123);      // write an integer
                       // to a new key
iniFile.WriteNumber("section1", "key5", -123);     // write a negative integer
                       // to a new key
iniFile.WriteNumber("section1", "key6", -123.456f);    // write a float to a new key
TestStruct writeTestStruct;
writeTestStruct.x = 6;
writeTestStruct.y = 7;
strcpy(writeTestStruct.charr, "abcdefg");
iniFile.WriteStruct("section1", "key7", &writeTestStruct, sizeof(TestStruct));

// Test the reading from the INI file
CString str;           // string that will receive the output
iniFile.GetString("section1", "key2", str, "default"); TRACE("key2=%s\n", str);
iniFile.GetString("section1", "nokey", str, "default");
   TRACE("nokey=%s\n", str); // non-existent key
iniFile.GetString("section3", "key1", str, "default"); TRACE("nokey=%s\n", str);
TRACE("key4=%d\n", iniFile.GetInt("section1", "key4", 0));
TRACE("key5=%d\n", iniFile.GetInt("section1", "key5", 0));
TRACE("key6=%f\n", iniFile.GetFloat("section1", "key6", 0));
TestStruct readTestStruct;
iniFile.GetStruct("section1", "key7", &readTestStruct, sizeof(TestStruct));
TRACE("key7= %ld %ld %s\n", readTestStruct.x,
   readTestStruct.y, readTestStruct.charr);
 // Test the section list retrieval
 CStringList lstSectionNames;
 for (POSITION pos = lstSectionNames.GetHeadPosition(); pos != NULL; )
  TRACE("\t%s\n", lstSectionNames.GetNext(pos));

Is there anything that should be fixed, added or removed in this project? Please let me know!


[1] A Small Class to Read INI File

[2] INI Class for .NET

[3] CIni

Revision History

Rev 0.1 Initial draft Nick Alexeev Nov 24, 2006
Rev 0.2 Added exception handling Nick Alexeev Nov 30, 2006


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Nick Alexeev
Systems Engineer Prolitech
United States United States
doing business as Prolitech
Redwood City, CA

blog (mostly technical)

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Comments and Discussions

QuestionErrors in VS2010 Pin
Tarun2221-May-12 22:47
memberTarun2221-May-12 22:47 
GeneralGetPrivateProfileString() in XP and Vista Pin
Roger Gonsalves6-Sep-09 17:51
memberRoger Gonsalves6-Sep-09 17:51 
Questionhow to Pin
pbturner9-May-07 6:38
memberpbturner9-May-07 6:38 
GeneralRe: how to [modified] Pin
Nick Alexeev9-May-07 8:15
memberNick Alexeev9-May-07 8:15 
GeneralRe: how to Pin
pbturner9-May-07 9:03
memberpbturner9-May-07 9:03 
GeneralThanks Pin
jfrancis21-Dec-06 14:52
memberjfrancis21-Dec-06 14:52 
GeneralRe: Thanks Pin
Nick Alexeev28-Jan-07 8:36
memberNick Alexeev28-Jan-07 8:36 
GeneralRe: Thanks Pin
nickhalfasleep24-Apr-07 11:20
membernickhalfasleep24-Apr-07 11:20 
QuestionHow many more do we need? Pin
Mark Nischalke25-Nov-06 3:54
memberMark Nischalke25-Nov-06 3:54 
AnswerRe: How many more do we need? Pin
Sceptic Mole26-Nov-06 2:00
memberSceptic Mole26-Nov-06 2:00 
AnswerRe: How many more do we need? Pin
CPallini30-Nov-06 22:21
memberCPallini30-Nov-06 22:21 
AnswerRe: How many more do we need? Pin
Abu Mami1-Dec-06 2:27
memberAbu Mami1-Dec-06 2:27 
AnswerRe: How many more do we need? Pin
Stephen Hewitt5-Dec-06 13:30
memberStephen Hewitt5-Dec-06 13:30 
GeneralRe: How many more do we need? Pin
Nick Alexeev5-Dec-06 21:17
memberNick Alexeev5-Dec-06 21:17 
GeneralA suggestion. Pin
cpallini25-Nov-06 1:57
membercpallini25-Nov-06 1:57 
GeneralRe: A suggestion. Pin
Nick Alexeev25-Nov-06 17:00
memberNick Alexeev25-Nov-06 17:00 
GeneralRe: A suggestion. Pin
cpallini25-Nov-06 23:06
membercpallini25-Nov-06 23:06 
GeneralRe: A suggestion. Pin
Nick Alexeev30-Nov-06 21:05
memberNick Alexeev30-Nov-06 21:05 
GeneralRe: A suggestion. Pin
CPallini30-Nov-06 22:20
memberCPallini30-Nov-06 22:20 
QuestionOrigional? Pin
WalderMort24-Nov-06 18:29
memberWalderMort24-Nov-06 18:29 
AnswerRe: Origional? [modified] Pin
Nick Alexeev24-Nov-06 18:43
memberNick Alexeev24-Nov-06 18:43 

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