a=77 *p=77 *p=123 a=123
(1) The way this program works is radically different from how its cousin program Puzzle P11 works. There are just a few characters different in the code, but they make a big difference. This might call for careful study.
(2) The function
newFunction()
and the caller
main()
must coordinate how values are passed.
The parameter list of
newFunction(int *p)
must match the arguments of its call,
newFunction( &a ).
(3) A function that has not been written to use pointer values can't
be called with pointers. There is no way that main()
can call the original function myfunction(int x) that
will enable that function to change a.