gcc/doc/gcc/extensions-to-the-c-language-family/arithmetic-on-void-and-function-pointers.rst

   1 ..
   2   Copyright 1988-2022 Free Software Foundation, Inc.
   3   This is part of the GCC manual.
   4   For copying conditions, see the copyright.rst file.
   5
   6 .. index:: void pointers, arithmetic, void, size of pointer to, function pointers, arithmetic, function, size of pointer to
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   8 .. _pointer-arith:
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  10 Arithmetic on void- and Function-Pointers
  11 *****************************************
  12
  13 In GNU C, addition and subtraction operations are supported on pointers to
  14 ``void`` and on pointers to functions.  This is done by treating the
  15 size of a ``void`` or of a function as 1.
  16
  17 A consequence of this is that ``sizeof`` is also allowed on ``void``
  18 and on function types, and returns 1.
  19
  20 .. index:: Wpointer-arith
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  22 The option :option:`-Wpointer-arith` requests a warning if these extensions
  23 are used.