Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>I think you need to write <code>~Derive()</code> like this</p> <pre><code>~Derived() { delete some; some = 0; //this is must; so that `delete some` in ~Base() works perfectly; //note `delete (void*)0` is fine in C++! } </code></pre> <p><strong>Explanation :</strong> </p> <p>Why you need to write this even though the <code>~Base()</code> does the same thing <em>(it looks it does the same thing)</em> is because <code>~Derived()</code> <em>ensures</em> that you delete your object from the <strong>same</strong> heap/memory-pool/etc they were created on.</p> <p>See these topics:</p> <p><a href="https://stackoverflow.com/questions/4555961/how-to-use-a-class-in-dll/4556092#4556092">How to use a class in DLL?</a><br> <a href="https://stackoverflow.com/questions/4534679/memory-management-with-returning-char-function/4534706#4534706">Memory Management with returning char* function</a> </p> <hr> <h1>EDIT:</h1> <p>Better would be to add one more virtual function, say <code>deinit()</code>, (a counter-part of your <code>virtual void init()</code>) , redefine this too when you redefine <code>init()</code>, and do the de-allocation there in <code>deinit()</code>.</p> <pre><code>//DLL class Base { protected: Something *some; public: virtual void init() { some = new Something(); } virtual void deinit() { delete some; } virtual ~Base() { deinit(); } }; //EXE class Derived : public Base { public: virtual void init() { some = new SomethingElse(); } virtual void deinit() { delete some; //some=0 is not needed anymore! } }; </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POWill the following cause problems with memory?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USCommunity
    1. USNawaz
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POWill the following cause problems with memory?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COBut if I do not what can happen?
      singulars
      1. PO
      1. USjmasterx
    2. CODeleting a null (0) pointer is ignored - deleting a valid pointer twice may cause crashes, depending on how brittle your operating system is.
      singulars
      1. PO
      1. USZooba
    3. CO@Milo : Zooba replied you already.:-)
      singulars
      1. PO
      1. USNawaz
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload