[Tutor] Variable Modification in a class

[Mehta, Anish]

I m sorry that i am repeating my last mail. Here also in c i m doing the 
same thing. Or is there any differnce? The point is clear to me that 
when i do ' c = b' it makes the memory locations same.

C example which is creating the confusion:

typedef struct ab
{
       int a;
       int b;
}AB;

main()
{
  AB b;
  AB c;

  b.a = 5;
  b.b = 10;

  c = b;

  c.a = 30;
  c.b = 40;

  printf("AB values %d %d\n", b.a, b.b);
  printf("New values %d %d\n", c.a, c.b);
}

The output is:

AB values 5 10
New values 30 40

Alan Trautman wrote:

>Let's try this:
>You can see that the assignment doesn't copy the values is assigns them by
>pointing to the same memory address.
>
>Try running this:
>
>class AB:
>    def __init__(self):
>        self.a = None
>        self.b = None
>
>def func(ab):
>    b = ab()
>    c = ab()
>    print "init c", c #memory locations prior to assignment
>    print "init b", b
>    print "these are different"
>    
>    b.a = 5
>    b.b = 10
>
>    c = b   # This block assigns c the same memory location as b
>            # This means any value placed in one will be in the other
>            # You have effectively lost b and any values that were
>            # assigned there
>    print "final c",c 
>    print "final b", b
>    c.a = 30
>    c.b = 40
>
>    print b.a, b.b
>    print c.a, c.b
>   
>t = func(AB)
>
>
>HTH,
>Alan
>
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