FreeEnvironmentStringsA function (processenv.h)

Frees a block of environment strings.


BOOL FreeEnvironmentStringsA(
  LPCH penv



A pointer to a block of environment strings. The pointer to the block must be obtained by calling the GetEnvironmentStrings function.

Return value

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero To get extended error information, call GetLastError.


If you used the ANSI version of GetEnvironmentStrings, be sure to use the ANSI version of FreeEnvironmentStrings. Similarly, if you used the Unicode version of GetEnvironmentStrings, be sure to use the Unicode version of FreeEnvironmentStrings.


For an example, see Changing Environment Variables.


The processenv.h header defines FreeEnvironmentStrings as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.


Requirement Value
Minimum supported client Windows XP [desktop apps | UWP apps]
Minimum supported server Windows Server 2003 [desktop apps | UWP apps]
Target Platform Windows
Header processenv.h (include Windows.h on Windows Server 2003, Windows Vista, Windows 7, Windows Server 2008 Windows Server 2008 R2)
Library Kernel32.lib
DLL Kernel32.dll

See also

Environment Variables