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C++ delete - It deletes my objects but I can still access the data?
Can a local variable's memory be accessed outside its scope?
I do not understand what delete really does when I want to free memory allocated with new. In C++ Premiere book it is written:
This removes the memory to which ps pointer points; it doesn’t remove the pointer ps itself. You can reuse ps, for example, to point to another new allocation. You should always balance a use of new with a use of delete; otherwise, you can wind up with a memory leak—that is, memory that has been allocated but can no longer be used. If a memory leak grows too large, it can bring a program seeking more memory to a halt.
So as I understand delete must delete the value in the memory to which pinter points. But it doesn't. Here's my experiment:
int * ipt = new int; // create new pointer-to-int
cout << ipt << endl; // 0x200102a0, so pointer ipt points to address 0x200102a0
cout << *ipt << endl; // 0, so the value at that address for now is 0. Ok, nothing was assigned
*ipt = 1000; // assign a value to that memory address
cout << *pt << endl; // read the new value, it is 1000, ok
cout << *((int *) 0x200102a0) << endl; // read exactly from the address, 1000 too
delete ipt; // now I do delete and then check
cout << ipt << endl; // 0x200102a0, so still points to 0x200102a0
cout << *ipt << endl; // 1000, the value there is the same
cout << *((int *) 0x200102a0) << endl; // 1000, also 1000 is the value
So what does delete really do?