--                       Decrement Operator (prefix and postfix)
 
 value--                 postfix decrement
 --value                 prefix decrement
   value                 any variable of type int, float, char, enum,
                           or related type
 
    The unary postfix operator -- decrements (subtracts one from ) lvalue
    after the expression containing lvalue has been evaluated. For
    example:
 
             j = 10; i = 5 * j--; /* i == 50, j == 9 */
 
    The unary prefix operator -- decrements lvalue before the expression
    containing lvalue has been evaluated. For example:
 
             j = 10; i = 5 * --j;  /* i == 45, j == 9 */
 
       Note:    In the case of pointers, -- moves the pointer to the
                previous element.  For example, if ptr is a pointer to a
                4-byte long, ptr-- actually subtracts 4 from ptr, thereby
                aiming it at the previous 4-byte long, not at the
                previous byte.  Decrementing a pointer to char always
                subtracts 1, on any machine.
 
                For pointers, both *(--lvalue) and lvalue[-1] fetch the
                same element. (We're not suggesting that you actually use
                a negative index.  Caveat Emptor.)

Seealso:


 ++