lispdoc - results for incf 

(incf place &optional (delta 1) &environment env)
Function: The first argument is some location holding a number. This number is incremented by the second argument, DELTA, which defaults to 1.
Example:
(defun get-counter ()
  "incremental counter to create unique numbers"
  (incf (wish-counter *wish*)))
Mentioned in:
CLtL2 - 12.4. Arithmetic Operations
CLtL2 - 16.1. Hash Table Functions
CLtL2 - 7.11. Dynamic Non-Local Exits
CLtL2 - 7.2. Generalized Variables
HyperSpec - Macro INCF, DECF
On Lisp - Anaphoric Macros (Macro-Defining Macros)
On Lisp - Applications for Macros
On Lisp - CLOS and Lisp
On Lisp - Classes and Instances
On Lisp - Functional Interfaces
On Lisp - Functions as Properties
On Lisp - New Utilities (Computation at Compile-Time)
On Lisp - Non-functional Expanders
On Lisp - Other Structures
On Lisp - When Capture Occurs
PCL - basic math
PCL - good object oriented design
PCL - other ways to modify places
PCL - training the filter
Successful Lisp - chapter20
(cffi:incf-pointer place &optional (offset 1) &environment env)
Undocumented
  

By Bill Moorier