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BSTR Functions
The Wxutil.h header file in the Microsoft® DirectShow base classes provides helper functions for allocating and freeing task-allocated BSTR strings.
Function Description FreeBSTR Frees the task-allocated BSTR string. WriteBSTR Creates a task-allocated BSTR string by allocating task-allocated memory and copying a wide string to it. BSTR Functions
FreeBSTRFrees a task-allocated BSTR string from memory.
STDAPI FreeBSTR(
BSTR* pstr
);Parameters
- pstr
- Address of the BSTR to free.
Return Values
Returns S_OK if successful, or S_FALSE if pstr is null.
Remarks
Memory is allocated for passing between objects across interfaces by calling CoTaskMemAlloc. It is freed by calling CoTaskMemFree. You can allocate, pass, and free memory safely between objects created in different programming languages by using a central memory allocator.
BSTR Functions
WriteBSTRAllocates and fills a task-allocated BSTR string.
STDAPI WriteBSTR(
BSTR* pstrDest,
LPCWSTR szSrc
);Parameters
- pstrDest
- Pointer to where the address of the allocated BSTR will be stored.
- szSrc
- Wide (Unicode) string that will be copied to the newly allocated BSTR string.
Return Values
Returns an HRESULT value.
Remarks
Memory is allocated for passing between objects across interfaces by calling CoTaskMemAlloc. It is freed by calling CoTaskMemFree. By using a central memory allocator, memory can be allocated, passed, and freed safely between objects created in different programming languages.
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