WriteProfileString

The WriteProfileString function copies a string into the specified section of the WIN.INI file.

This function is provided for compatibility with 16-bit Windows-based applications. Win32-based applications should store initialization information in the registry.

BOOL WriteProfileString(
  LPCTSTR lpAppName, // pointer to section name
  LPCTSTR lpKeyName, // pointer to key name
  LPCTSTR lpString   // pointer to string to write
);
 

Parameters

lpAppName

Pointer to a null-terminated string that specifies the section to which the string is to be copied. If the section does not exist, it is created. The name of the section is not case-sensitive; the string can be any combination of uppercase and lowercase letters.

lpKeyName

Pointer to a null-terminated string containing the key to be associated with the string. If the key does not exist in the specified section, it is created. If this parameter is NULL, the entire section, including all entries in the section, is deleted.

lpString

Pointer to a null-terminated string to be written to the file. If this parameter is NULL, the key pointed to by the lpKeyName parameter is deleted.

Windows 95: The system does not support the use of the TAB (\t) character as part of this parameter.

Return Values

If the function successfully copies the string to the WIN.INI file, the return value is nonzero.

If the function fails, or if it flushes the cached version of WIN.INI, the return value is zero. To get extended error information, call GetLastError.

Remarks

Windows 95: Windows 95 keeps a cached version of WIN.INI to improve performance. If all three parameters are NULL, the function flushes the cache. The function always returns FALSE after flushing the cache, regardless of whether the flush succeeds or fails.

A section in the WIN.INI file must have the following form:

[section]
key=string
    .
    .
    . 
 

Windows NT: Windows NT 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

When the operation has been mapped, the WriteProfileString function writes information to the registry, not to the initialization file; the change in the storage location has no effect on the function's behavior.

The Win32 profile functions (Get/WriteProfile*, Get/WritePrivateProfile*) use the following steps to locate initialization information:

1. Look in the registry for the name of the initialization file, say MYFILE.INI, under IniFileMapping:

   HKEY_LOCAL_MACHINE\Software\Microsoft\
   Windows NT\CurrentVersion\IniFileMapping\myfile.ini

2. Look for the section name specified by lpAppName. This will be a named value under myfile.ini, or a subkey of myfile.ini, or will not exist.
3. If the section name specified by lpAppName is a named value under myfile.ini, then that value specifies where in the registry you will find the keys for the section.
4. If the section name specified by lpAppName is a subkey of myfile.ini, 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.
5. If the section name specified by lpAppName does not exist as a named value or as a subkey under myfile.ini, then there will be an unnamed value (shown as <No Name>) under myfile.ini that specifies the default location in the registry where you will find the keys for the section.
6. If there is no subkey for MYFILE.INI, or if there is no entry for the section name, then look for the actual MYFILE.INI 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.

See Also

Registry Overview, Registry Functions, GetProfileString, WritePrivateProfileString