Question

I would like to ask if I’s correct the following :

MyClass *obj = new MyClass();//allocate memory

obj.Variab="HELLO";

obj=NULL;
delete obj; //free memory

Is the memory allocated for obj deleted after the last two sentences? Appreciate.THX
I would like to mention that I am working in c++ /Ubuntu. G++ is the compiler

EDIT:

What if I have?

int i=0;
list<string>l;
while (i<100)
{  
    MyClass *obj = new MyClass();//allocate memory
    obj->Variab="HELLO";
    //add the obj.valie in a list 
    l.push_back(obj);
    i=i+1;

delete obj; //free memory

}

it is ok?

Answer 1

no, you should use delete before assigning to NULL

delete obj; //free memory 
obj=NULL;

this is becasue the actual parameter to delete is the address of the allocated memory, but if you assign NULL before delete is used, you are actually passing NULL to delete, and nothing will happen, and you will get yourself a memory leak.

---

your edit question:

this code will not compile, as obj is not defined outside the while scope, in any case, also, l is a list<string> and you are trying to insert MyClass* types,this will result in another compilation error. also, you should use obj->Variab and not obj.Variab, since obj is a pointer.

EDIT to EDIT:

well, you still got a compilation error, since obj is not defined when you are trying to delete it. try this:

#include <iostream>
#include <list>
using namespace std;
class MyClass {
public:
    string Variab;
};

void myfunction (const string& s) {
  cout << " " << s;
}

int main()
{
    int i=0;
    list<string>l;
    while (i<100) {
        MyClass *obj = new MyClass();//allocate memory
        obj->Variab="HELLO";
        l.push_back(obj->Variab);
        i=i+1;
        delete obj; //free memory
    }
    for_each (l.begin(), l.end(), myfunction);

}