Expert: Narendra - 8/28/2006

Question


hello sir

i he problem in this code
Q------>1.
int *p,x;
x=5;
p=&x;
cout<<*p;  // ist
delete(p);
cout << *p; // iind


in both the cases ist and iind stmt print correct value
even after delete operation ? is this is the problem of memory leak or something else ?

Q-------> 2
int *ptr=5;
is this is valid stmt , or if yes then 5 will store where ? we havent give any storage area or it takes storage from any where

make it clear ?

thank you
monika

Answer
Looks like your pointers basics is not yet clear!

1. Here you are doing delete() without performing new().
  Only if you did a new() before, delete() will be valid.
  But, your computer will not be able to tell whether the call is valid or not.
  It would have maintained a linked list of addresses that you have allocated using new().
  So, when you do delete(), it may refer that list and delete the address.
  Since you haven't done new(), the linked list is empty and hence delete() didn't do anything.

2. When you do:
int *ptr = 5;
  You are trying to assign the address 5 to ptr.
  This is just like:
int *ptr = (int *) malloc(1);
  If you do malloc (or new() in C++), the system will assign you a valid address from the heap.
  But, now you are doing your memory management and assigning 5 to ptr.
  So, it is your responsibility to see to it that, 5 is a valid address and is writable.
  Otherwise, your program will just do wrong things and will crash.