Classic VB - How can I read/write an .Ini file?

[dee-u]

There are several functions built into the Windows API to help work with Ini files, the code below includes "wrapper" functions which you can use to work with them.

This code should be pasted into the General Declarations section of your form/module

'declarations for working with Ini files
Private Declare Function GetPrivateProfileSection Lib "kernel32" Alias _
    "GetPrivateProfileSectionA" (ByVal lpAppName As String, ByVal lpReturnedString As String, _
    ByVal nSize As Long, ByVal lpFileName As String) As Long
 
Private Declare Function GetPrivateProfileString Lib "kernel32" Alias _
    "GetPrivateProfileStringA" (ByVal lpApplicationName As String, ByVal lpKeyName As Any, _
    ByVal lpDefault As String, ByVal lpReturnedString As String, ByVal nSize As Long, _
    ByVal lpFileName As String) As Long
 
Private Declare Function WritePrivateProfileSection Lib "kernel32" Alias _
    "WritePrivateProfileSectionA" (ByVal lpAppName As String, ByVal lpString As String, _
    ByVal lpFileName As String) As Long
 
Private Declare Function WritePrivateProfileString Lib "kernel32" Alias _
    "WritePrivateProfileStringA" (ByVal lpApplicationName As String, ByVal lpKeyName As Any, _
    ByVal lpString As Any, ByVal lpFileName As String) As Long
 
'// INI CONTROLLING PROCEDURES
'reads an Ini string
Public Function ReadIni(Filename As String, Section As String, Key As String) As String
Dim RetVal As String * 255, v As Long
  v = GetPrivateProfileString(Section, Key, "", RetVal, 255, Filename)
  ReadIni = Left(RetVal, v - 1)
End Function
 
'reads an Ini section
Public Function ReadIniSection(Filename As String, Section As String) As String
Dim RetVal As String * 255, v As Long
  v = GetPrivateProfileSection(Section, RetVal, 255, Filename)
  ReadIniSection = Left(RetVal, v - 1)
End Function
 
'writes an Ini string
Public Sub WriteIni(Filename As String, Section As String, Key As String, Value As String)
  WritePrivateProfileString Section, Key, Value, Filename
End Sub
 
'writes an Ini section
Public Sub WriteIniSection(Filename As String, Section As String, Value As String)
  WritePrivateProfileSection Section, Value, Filename
End Sub

Example usage:

Private Sub Form_Load()
 
Dim File As String, OFLen As Double,  Str As String
 
  File = "C:\temp.ini"
  OFLen = FileLen(File)
 
    'write a few example sections:
  WriteIniSection File, "Test1", ""
  WriteIniSection File, "Test2", "Here shoud be found some text"
 
    'write a few ini strings
  WriteIni File, "Test3", "Ini1", "This is ini 1"
  WriteIni File, "Test1", "Ini2", "This is ini 2"
 
    'test message - inform we've written the data
  MsgBox Format((FileLen(File) - OFLen) / 1024, "0.00") & " KB data written to " & Chr(34) & File & Chr(34)
 
    'read the ini file
  Str = Str & "Test2 section: " & vbTab & ReadIniSection(File, "Test2") & vbCrLf
  Str = Str & "Test1 section: " & vbTab & ReadIniSection(File, "Test1") & vbCrLf
  Str = Str & "Ini1 string: " & vbTab & ReadIni(File, "Test3", "Ini1") & vbCrLf
  Str = Str & "Ini2 string: " & vbTab & ReadIni(File, "Test1", "Ini2") & vbCrLf
 
    'show the data from the file
  MsgBox Str
 
End Sub

[batori]

this code does work but it does not give back the entire string form the ini...one last char is missing most of the times. ..

[LaVolpe]

this code does work but it does not give back the entire string form the ini...one last char is missing most of the times. ..

The problem here is that if more than 254 characters were written to the INI then the ReadINI function will truncate to 254 characters, as the function is written. Also the return value (if successful) is not one less than the length of the string, so subtracting 1 from it is inappropriate.

The API returns Len(String)-1 if Section & Key parameters are passed and the string sent to the API isn't big enough for the returned value. The workaround is to test the return value and resize the passed string until the API return value meets a specific criteria...

Public Function ReadIni(Filename As String, Section As String, Key As String) As String

    Dim RetVal As String, v As Long
    Dim retLen As Long
    
    Do
        retLen = retLen + 260 ' arbitrary - can be set higher/lower if desired
        RetVal = Space(retLen)
        v = GetPrivateProfileString(Section, Key, "", RetVal, retLen, Filename)
    Loop Until v < retLen - 1 
    
    ReadIni = Left$(RetVal, v)

End Function