A void pointer, written void*, holds the address of an object without retaining the object’s type information. Any object pointer converts to void* and back; converting back to the same type preserves the pointer value. TAKEAWAY: the conversion removes type information, not the object’s value. section 12.4
Generic storage with malloc
A dynamically allocated vector can use the type-specific pointer only where it matters: double *largeVec = malloc(living * sizeof *largeVec); malloc returns void*, but C converts that object pointer automatically to double*. The sizeof *largeVec expression supplies the size of one double without repeating the type, while malloc itself operates in bytes and knows nothing about the eventual type. Release the storage with free(largeVec) when it is no longer needed. Do not attempt a very large allocation merely to reproduce the example; first compute its required size and assess whether it is feasible. section 13.1
Use void* narrowly and keep these rules visible:
- Treat void* as a pointer into storage whose original type is temporarily abstracted away. section 12.4
- Remember that the conversion guarantee applies to object pointers, not function pointers. section 12.4
- Avoid void* when a more specific pointer type is available; do not declare variables with void alone as their type. section 12.4
