Pointer and new Question

Hallo,

What is the difference between:

Code:

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someClass *ptr = new someClass;

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and

Code:

---

someClass temp;
someClass *ptr = &temp;

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To me the last one looks a lot better, as I have heard the new is a slow command, and that when you use new you also need to have delete. But I am feeling that I am missing something here...

Thanks

The first one points to allocated memory, the second one points to an automatic(?).

Quote:

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Originally Posted by h3ro

Hallo,

What is the difference between:

Code:

---

someClass *ptr = new someClass;

---

and

Code:

---

someClass temp;
someClass *ptr = &temp;

---

To me the last one looks a lot better, as I have heard the new is a slow command, and that when you use new you also need to have delete. But I am feeling that I am missing something here...

Thanks

---

New dynamically allocates memory that won't be removed until delete is called on the pointer. What happens when temp goes out of scope? What will ptr point to then?

A pointer is just a variable that holds an address. In the first, new allocates memory and returns a pointer to that new memory. The second assigns the address from a stack variable to the pointer.