GetPrivateProfileString function (winbase.h)

Article
09/22/2022

Retrieves a string from the specified section in an initialization file.

Note This function is provided only for compatibility with 16-bit Windows-based applications. Applications should store initialization information in the registry.

Syntax

DWORD GetPrivateProfileString(
  [in]  LPCTSTR lpAppName,
  [in]  LPCTSTR lpKeyName,
  [in]  LPCTSTR lpDefault,
  [out] LPTSTR  lpReturnedString,
  [in]  DWORD   nSize,
  [in]  LPCTSTR lpFileName
);

Parameters

[in] lpAppName

The name of the section containing the key name. If this parameter is NULL, the GetPrivateProfileString function copies all section names in the file to the supplied buffer.

[in] lpKeyName

The name of the key whose associated string is to be retrieved. If this parameter is NULL, all key names in the section specified by the lpAppName parameter are copied to the buffer specified by the lpReturnedString parameter.

[in] lpDefault

A default string. If the lpKeyName key cannot be found in the initialization file, GetPrivateProfileString copies the default string to the lpReturnedString buffer.

If this parameter is NULL, the default is an empty string, "".

Avoid specifying a default string with trailing blank characters. The function inserts a null character in the lpReturnedString buffer to strip any trailing blanks.

[out] lpReturnedString

A pointer to the buffer that receives the retrieved string.

[in] nSize

The size of the buffer pointed to by the lpReturnedString parameter, in characters.

[in] lpFileName

The name of the initialization file. If this parameter does not contain a full path to the file, the system searches for the file in the Windows directory.

Return value

The return value is the number of characters copied to the buffer, not including the terminating null character.

If neither lpAppName nor lpKeyName is NULL and the supplied destination buffer is too small to hold the requested string, the string is truncated and followed by a null character, and the return value is equal to nSize minus one.

If either lpAppName or lpKeyName is NULL and the supplied destination buffer is too small to hold all the strings, the last string is truncated and followed by two null characters. In this case, the return value is equal to nSize minus two.

In the event the initialization file specified by lpFileName is not found, or contains invalid values, calling GetLastError will return '0x2' (File Not Found). To retrieve extended error information, call GetLastError.

Remarks

The GetPrivateProfileString function searches the specified initialization file for a key that matches the name specified by the lpKeyName parameter under the section heading specified by the lpAppName parameter. If it finds the key, the function copies the corresponding string to the buffer. If the key does not exist, the function copies the default character string specified by the lpDefault parameter. A section in the initialization file must have the following form:

[section]
key=string
      .
      .
      .

If lpAppName is NULL, GetPrivateProfileString copies all section names in the specified file to the supplied buffer. If lpKeyName is NULL, the function copies all key names in the specified section to the supplied buffer. An application can use this method to enumerate all of the sections and keys in a file. In either case, each string is followed by a null character and the final string is followed by a second null character. If the supplied destination buffer is too small to hold all the strings, the last string is truncated and followed by two null characters.

If the string associated with lpKeyName is enclosed in single or double quotation marks, the marks are discarded when the GetPrivateProfileString function retrieves the string.

The GetPrivateProfileString function is not case-sensitive; the strings can be a combination of uppercase and lowercase letters.

To retrieve a string from the Win.ini file, use the GetProfileString function.

The system maps most .ini file references to the registry, using the mapping defined under the following registry key:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\IniFileMapping

This mapping is likely if an application modifies system-component initialization files, such as Control.ini, System.ini, and Winfile.ini. In these cases, the function retrieves information from the registry, not from the initialization file; the change in the storage location has no effect on the function's behavior.

The profile functions use the following steps to locate initialization information:

Look in the registry for the name of the initialization file under the IniFileMapping key.
Look for the section name specified by lpAppName. This will be a named value under the key that has the name of the initialization file, or a subkey with this name, or the name will not exist as either a value or subkey.
If the section name specified by lpAppName is a named value, then that value specifies where in the registry you will find the keys for the section.
If the section name specified by lpAppName is a subkey, then named values under that subkey specify where in the registry you will find the keys for the section. If the key you are looking for does not exist as a named value, then there will be an unnamed value (shown as <No Name>) that specifies the default location in the registry where you will find the key.
If the section name specified by lpAppName does not exist as a named value or as a subkey, then there will be an unnamed value (shown as <No Name>) that specifies the default location in the registry where you will find the keys for the section.
If there is no subkey or entry for the section name, then look for the actual initialization file on the disk and read its contents.

When looking at values in the registry that specify other registry locations, there are several prefixes that change the behavior of the .ini file mapping:

! - this character forces all writes to go both to the registry and to the .ini file on disk.
# - this character causes the registry value to be set to the value in the Windows 3.1 .ini file when a new user logs in for the first time after setup.
@ - this character prevents any reads from going to the .ini file on disk if the requested data is not found in the registry.
USR: - this prefix stands for HKEY_CURRENT_USER, and the text after the prefix is relative to that key.
SYS: - this prefix stands for HKEY_LOCAL_MACHINE\SOFTWARE, and the text after the prefix is relative to that key.

Example

The following example demonstrates the use of GetPrivateProfileString.

// Gets a profile string called "Preferred line" and converts it to an int.
GetPrivateProfileString (
      "Preference",
      "Preferred Line",
      gszNULL, 
      szBuffer,
      MAXBUFSIZE,
      gszINIfilename
);

// if szBuffer is not empty.
if ( lstrcmp ( gszNULL, szBuffer ) )
{
      dwPreferredPLID = (DWORD) atoi( szBuffer );	
}
else	
{
      dwPreferredPLID = (DWORD) -1;
}

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	winbase.h (include Windows.h)
Library	Kernel32.lib
DLL	Kernel32.dll