Question

Consider this piece of code:

int *a, *b;
a = foo();
if (a)
   b = a;
a = bar();

The problem is, when a updates by calling bar(), b also updates. However I want to make a backup by using b = a. What is the problem then?

Answer 1

int *a, *b;
b = new int;

a = foo();
if (a)
   *b = *a;
a = bar();
...
delete(b);

(The value at address a is assigned to the value at address b.)

What you are doing right now is making a and b point to the same place in memory. Then, if the value in a or b is updated, they pointers both point to the new value.

By the way, unless bar() returns a pointer, you probably want *a = foo() and *a = bar().