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I will give some examples and explain. First, I declare some object like

CString* param = new CString[100]

And when I declare this one, my memory would increase a little bit because it's some implemented string. Then I store this object in some list of CString just like

List<CString> myList = new List<CString>; // new list of CString

myList.add(param);

This is my question: I wanna know, when I delete myList, my param isn't deleted, right? And memory in param still exists.

Do I misunderstand?

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  • You are adding CString object when you say List<CString> myList, I don't think so this is best way. store pointers and you are allocating CString and its you responsibility to release it. Also I have doubt your code is compiling successfully? Commented Sep 17, 2012 at 9:27
  • what kind of list is this? MFC? Commented Sep 17, 2012 at 9:32
  • 1
    Note that C++ is not Java, especially new is used differently in C++. Commented Sep 17, 2012 at 9:34
  • Impossible to answer, without seeing the definition of List. Apparently it has a constructor that takes a List*, and when instantiated on a type, it traffics in pointers to that type. Quite an odd class... Commented Sep 17, 2012 at 13:26

2 Answers 2

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That code won't compile because myList holds objects, not pointers, and because myList is an object, not a pointer, so new is illegal there:

List<CString> myList; is an object of type List<CString>. new List<CString>; returns a List<CString>*. param is a CString*. myList.add() expects a CString, not a CString*.

Bottom line: these are all basic concepts, grab a good book and read it. C++ is a complicated language, you can't just learn it from example snippets or assume the same concepts and syntax are the same as other languages.

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5 Comments

I'm sorry about my code. My intention about that list is some pointer list which add parameter param and when I delete this list, memory from param is still exist. isn't it?
@barssala the code doesn't even compile, so it can't even run. You can't talk about runtime behavior when you can't even start the program.
@barssala but in theory, no, if you allocate with new[], you have to explicitly delete with delete[].
Ok, if it's not a list. If I use CString* a = param and delete a. What's about that? I mean param still exist? Because I delete only obj. a.
@barssala a is a pointer, not an object. And a and param would point to the same location, so both would be invalid after the delete. Take my advice and read a book. ;)
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Rule of thumb for c++ : If you type new you'll need a delete, except if you're using some kind of smart pointer.

Notice in your case you'll need to use 

delete [] param ;

As you are deleting an array.

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8 Comments

There are some one new object in function. And I can't delete that parameters directly.<br/> I will give you some examples. <br/> void test(){ CString* param("sth"); myString = param;//myString is parameters in header file } and I wanna know that object param in function will exist forever? and I can't delete param because if I delete param, it will cause myString be NULL as well.
I don't know what CString is. And how you can compare it's pointer to a non pointer string.
CString is my implemented string and myString is defined in header file like CString* myString.
Still i don't understand how you can compare a pointer type to a non pointer type. If MyString i also a pointer you can delete him instead of param.
My CString declare in header file such as CString* myString. So, myString is a pointer.
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