incf-pointer Function

Summary

Increases the address held by a pointer.

Package

fli

Signature

incf-pointer pointer &optional delta => pointer

Arguments

Values

Description

The function incf-pointer increases the address held by pointer. If delta is not given the address is increased by the size of the type pointed to by pointer. The address can be increased by a multiple of the size of the type by specifying a delta. If the size of the type is 0 then an error is signalled.

The function incf-pointer is often used to move a pointer through an array of values.

Examples

In the following example an array with 10 entries is defined. A copy of the pointer to the array is made, and is incremented and decremented.

(setq array-obj
      (fli:allocate-foreign-object :type :int
        :nelems 10
        :initial-contents '(0 1 2 3 4 5 6 7 8 9)))
 
(setq point1 (fli:copy-pointer array-obj))
 
(dotimes (x 9) 
  (print (fli:dereference point1))
  (fli:incf-pointer point1))
 
(dotimes (x 9) 
  (fli:decf-pointer point1)
  (print (fli:dereference point1)))

See also

decf-pointer
3.4 An example of dynamic pointer allocation