XtRealloc()XtRealloc()NameXtRealloc - change the size of an allocated block of storage.
Synopsis
char *XtRealloc(ptr, num);
char *ptr;
Cardinal num;
Inputs
ptr Specifies a pointer to memory allocated with XtMalloc(),
XtCalloc(), or XtRealloc(), or NULL.
num Specifies the new number of bytes of memory desired in the
block.
Returns
A pointer to allocated memory.
DescriptionXtRealloc() changes the size of the block of allocated memory pointed
to by ptr to be at least num bytes large. In order to make this size
change, it may have to allocate a new block of memory and copy the con‐
tents of the old block (or as much as will fit) into the new block. If
it allocates a new block of memory, it frees the old block. In either
case, it returns a pointer to a block of memory which is of the
requested size. If there is insufficient memory to allocate the new
block, XtRealloc() terminates by calling XtErrorMsg().
If ptr is NULL, XtRealloc() simply calls XtMalloc() to allocate a block
of memory of the requested size.
Usage
Note that XtRealloc() may move the contents of your allocated memory to
a new location; the return value may or may not be the same as ptr.
Not all memory can be safely reallocated. If there are multiple point‐
ers to a block of memory scattered through out an application (such as
pointers to a widget record), then reallocating that memory is not
safe, because all pointers to it cannot be updated. Other memory (such
as the array of children maintained privately by the Composite widget
class) can be safely updated because there should be only one pointer
to it in the application (in this case the pointer is the compos‐
ite.children field of the widget). These cautions are no different
than those required with the standard realloc() function.
In most cases, you will have to cast the return value of XtRealloc() to
an appropriate pointer type.
Note that because XtRealloc() behaves like XtMalloc() when passed a
NULL pointer, (something that realloc() does not do), you don't have to
write special case code to allocate the first chunk of memory with
XtMalloc() and subsequent chunks with XtRealloc(); you can simply use
XtRealloc() everywhere.
Memory allocated with XtRealloc() must be deallocated with XtFree().
The function XtRealloc() is implemented by the Toolkit independently of
the particular environment, so programs ported to a system not support‐
ing malloc will still work.
See AlsoXtCalloc(1), XtFree(1), XtMalloc(1), XtNew(1), XtNewString(1).
Xt - Memory Allocation XtRealloc()
