constvoidpointer

In C and C++, a const void pointer refers to a pointer to a const object of unspecified type. The type is written as const void* (or void const*). The const qualifier applies to the data pointed to, not to the pointer itself; thus you can assign a different address to the pointer, but you cannot modify the object through this pointer.

Because the pointed-to type is void, you cannot dereference the pointer directly to read or write the value. To access the data you must cast the pointer to a pointer to a concrete type, such as const int* or const char*. Casts allow reading the data, but you must respect the original object's const-ness.

Common use cases include generic APIs that operate on raw memory or buffers without committing to a specific type, such as interfaces that accept a const void* data and a size. For example, functions like memcpy take a const void* source, enabling them to read bytes from memory without knowing the exact type.

Pointer arithmetic on a void pointer is not defined in standard C; to move through bytes, you cast to a pointer to a complete type (usually char* or unsigned char*) and perform arithmetic there.

Equivalence and related qualifiers: void const* is the same as const void*. A const qualifier on the pointer itself would produce void* const, which means the pointer cannot be reseated but the pointed-to data may be modifiable (if not also const).

In practice, const void* conveys read-only, type-erased data, enabling generic interfaces while preserving type safety by requiring a cast back to a concrete type when accessing the underlying object.