A.4 Conversion to void *
Note
In C, there is a standard conversion from void * to T *
(for any object type T). In C++, there is no such
conversion. Such conversions require a cast in C++.
The following Standard C library functions return void *:
calloc, malloc, realloc, bsearch, memcpy, memmove,
memchr, memset
C++ requires an explicit cast when assigning the return
value of such a function to a pointer to non-void type.
Example
int* p;
p = malloc(10 * sizeof(int));
In C++, the assignment to p requires an explicit cast, as
in
p = (int *)malloc(10 * sizeof(int));
Guideline
In C++, use operator new instead of calloc, malloc, or
realloc. (See item A.12).
Ignore the return value of a memcpy, memmove, and memset.
(They just return their first argument converted to void
*.)
For all other functions that return void * (standard or
user-defined), use an explicit cast when converting the
return value to another pointer type.
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