c/experimental/dynamic/asprintf

@1@ Analog of sprintf, except that it allocates a storage large enough to hold the output including the terminating null character, as if by a call to malloc, and returns a pointer to that storage via the first argument. This pointer should be passed to free to release the allocated storage when it is no longer needed.

@2@ Same as, except that it works with wide characters wchar_t (by analogy with swprintf).

@3@ Same as, with the variable argument list replaced by , which shall be initialized by the va_start macro (and possibly subsequent va_arg calls).

@4@ Same as, except that it works with wide characters wchar_t.

Return value
The number of characters written, just like sprintf, swprintf , vsprintf , or vswprintf , respectively. If memory allocation wasn't possible, or some other error occurs, these functions will return, and the contents of is undefined.