LPVOID

The LPVOID type is a generic pointer type defined in the Windows API. It is used to represent a pointer to any data type. In C/C++, it is typically defined as void *.

Definition


                        typedef void * LPVOID;

Description

LPVOID is a generic pointer that can point to any memory location. This is particularly useful when a function needs to accept a pointer to data without knowing the specific type of that data in advance. When you use LPVOID, you are responsible for casting it to the correct pointer type before dereferencing it to access the data.

The LP prefix in LPVOID historically stood for "long pointer," a concept relevant in older Windows architectures (like 16-bit) where there was a distinction between near and far pointers. In modern 32-bit and 64-bit Windows, this distinction is largely obsolete, and LPVOID behaves like a standard pointer.

Usage

LPVOID is commonly used in Windows API functions for parameters that can accept various data structures or data buffers. For example, in memory management functions, configuration functions, or callback mechanisms.

Example: Generic Memory Copy Function (Conceptual)

                    
                        // This is a conceptual example to illustrate LPVOID usage.
                        // Actual WinAPI functions have specific parameter types.

                        void CopyMemoryGeneric(
                            LPVOID pDestination,
                            const LPVOID pSource,
                            SIZE_T size
                        )
                        {
                            // In a real implementation, you would cast and perform byte-by-byte copy
                            BYTE *dest_ptr = reinterpret_cast<BYTE *>(pDestination);
                            const BYTE *src_ptr = reinterpret_cast<const BYTE *>(pSource);

                            for (SIZE_T i = 0; i < size; ++i) {
                                dest_ptr[i] = src_ptr[i];
                            }
                        }
                    
                

Important: Always ensure you know the actual data type being pointed to by an LPVOID and cast it correctly before performing any operations on the data. Incorrect casting can lead to undefined behavior and crashes.

Related Types

PVOID: Similar to LPVOID, also a generic pointer. Often used interchangeably in modern code, though LPVOID has historical implications.
VOID: The unqualified void type, used as a return type for functions that don't return a value.

MSDN Documentation