Like @code{vsprintf}, but instead of passing a pointer to a buffer,
you pass a pointer to a pointer. This function will compute the size
of the buffer needed, allocate memory with @code{malloc}, and store a
pointer to the allocated memory in @code{*@var{resptr}}. The value
returned is the same as @code{vsprintf} would return. If memory could
Like @code{vsprintf}, but instead of passing a pointer to a buffer,
you pass a pointer to a pointer. This function will compute the size
of the buffer needed, allocate memory with @code{malloc}, and store a
pointer to the allocated memory in @code{*@var{resptr}}. The value
returned is the same as @code{vsprintf} would return. If memory could