-- card: 35573 from stack: in
-- bmap block id: 0
-- flags: 0000
-- background id: 4755
-- name: 


-- part contents for background part 4
----- text -----
with the function pointer, although ANSI C allows the '*' to be omitted!  The following function takes one function pointer and one float as arguments, and returns the result of applying the function pointed to by the function pointer twice.

    float  perform_twice(float (*func_ptr)(float),float value)
    {
        return (*func_ptr)((*func_ptr)(value));
    }

The calling function passes the address of the desired function as an argument to the called function.  As with array identifiers, the function identifier itself represents its address - the '&' operator is not needed.  The calling function may pass the square() function to perform_twice() as an argument, in order to find the 4th power of a value:

    fourth_power = perform_twice(square,original_value);


-- part contents for background part 7
----- text -----
99