The XtMalloc functions returns a pointer to a block of storage of at least the specified size bytes. If
there is insufficient memory to allocate the new block, XtMalloc calls XtErrorMsg.
The XtCalloc function allocates space for the specified number of array elements of the specified size
and initializes the space to zero. If there is insufficient memory to allocate the new block, XtCalloc
calls XtErrorMsg.
The XtRealloc function changes the size of a block of storage (possibly moving it). Then, it copies the
old contents (or as much as will fit) into the new block and frees the old block. If there is
insufficient memory to allocate the new block, XtRealloc calls XtErrorMsg. If ptr is NULL, XtRealloc
allocates the new storage without copying the old contents; that is, it simply calls XtMalloc.
The XtFree function returns storage and allows it to be reused. If ptr is NULL, XtFree returns
immediately.
XtNew returns a pointer to the allocated storage. If there is insufficient memory to allocate the new
block, XtNew calls XtErrorMsg. XtNew is a convenience macro that calls XtMalloc with the following
arguments specified:
((type *) XtMalloc((unsigned) sizeof(type))
XtNewString returns a pointer to a new string which is a duplicate of string. If there is insufficient
memory to allocate the new block, or the argument is NULL XtNewString returns NULL. The memory can be
freed with XtFree.
The XtAsprintf function allocates space for a string large enough to hold the string specified by the
sprintf(3c) format pattern when used with the remaining arguments, and fills it with the formatted
results. The address of the allocated string is placed into the pointer passed as ret. The length of
the string (not including the terminating null byte) is returned. If there is insufficient memory to
allocate the new block, XtAsprintf calls XtErrorMsg.