_CrtIsValidPointer

Verifies that a pointer isn't null. In versions of the C run-time library before Visual Studio 2010, verifies that a specified memory range is valid for reading and writing (debug version only).

Syntax

int _CrtIsValidPointer(
   const void *address,
   unsigned int size,
   int access
);

Parameters

address
Points to the beginning of the memory range to test for validity.

size
Size of the specified memory range (in bytes).

access
Read/write accessibility to determine for the memory range.

Return value

_CrtIsValidPointer returns TRUE if the specified pointer isn't null. In CRT library versions before Visual Studio 2010, returns TRUE if the memory range is valid for the specified operation or operations. Otherwise, the function returns FALSE.

Remarks

In the CRT library in Visual Studio 2010 and later versions, the size and access parameters are ignored, and _CrtIsValidPointer only verifies that the specified address isn't null. Because this test is easy to perform yourself, we don't recommend you use this function. In versions before Visual Studio 2010, the function verifies that the memory range beginning at address and extending for size bytes is valid for the specified accessibility operation or operations. When access is set to TRUE, the memory range is verified for both reading and writing. When access is FALSE, the memory range is only validated for reading. When _DEBUG isn't defined, calls to _CrtIsValidPointer are removed during preprocessing.

Because this function returns TRUE or FALSE, it can be passed to one of the _ASSERT macros to create a basic debugging error handling mechanism. The following example causes an assertion failure if the memory range isn't valid for both reading and writing operations:

_ASSERTE( _CrtIsValidPointer( address, size, TRUE ) );

For more information about how _CrtIsValidPointer can be used with other debug functions and macros, see Macros for reporting. For information about how memory blocks are allocated, initialized, and managed in the debug version of the base heap, see CRT debug heap details.

Requirements

_CrtIsValidPointer is a Microsoft extension. For compatibility information, see Compatibility.

Libraries

Debug versions of C run-time libraries only.

Example

See the example for the _CrtIsValidHeapPointer article.

See also

Debug routines