Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Do as follows:</p> <pre><code>#include &lt;cstddef&gt; template &lt;typename T&gt; class Array { public: T* const arrayPointer; // arrayPointer can't be reallocated const size_t size; // size can't change Array(const int theSize) : arrayPointer(new T[theSize]), size(theSize) {} ~Array() { delete[] arrayPointer; } private: Array(const Array&amp; other) {} // forbid copy Array&amp; operator= (const Array&amp; other) {} // forbid assignment } ; </code></pre> <ul> <li>Why to use <code>template &lt;typename T&gt;</code>? So you can have an array of any type.</li> <li>Why to use <code>new T[ theSize ]</code> ? So you can allocate <code>theSize</code> elements at the same time.</li> <li>Why to use <code>: arrayPointer( new T[ theSize ])</code> ? So in case allocation fails (due to big theSize) the object fails without initialization. It is callled RAII.</li> <li>Why to use <code>delete [] arrayPointer</code> ? Because you used <code>new[]</code> and you have to deallocate the whole array.</li> <li>Why those <code>const</code>'s? To avoid anyone changing the size of the array and making the fields inconsistent.</li> <li>What are these private methods? They are forbiding copies, so no one can make <code>array1 = array2; delete array2;</code>, what would deallocate the arrayPointer of array1.</li> </ul> <p>Usage (it will allocate array of 10 int:)</p> <pre><code>Array&lt; int &gt; arr( 10 ) ; </code></pre> <p>Access:</p> <pre><code>arr.arrayPointer[ 0 ] = 5 ; </code></pre> <p>Note - you can access <code>arrayPointer</code> at the cells of range 0..9. You can add <code>operator[]</code> to your class in order to avoid using <code>arrayPointer</code> and to use <code>arr[ 0 ]</code>.</p>
    singulars
    1. This table or related slice is empty.
    1. POFreeing memory with Pointer Arithmetic
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USAlex Oliveira
    1. USGrzegorz
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    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. VTApproveEditSuggestion
    1. COThis is also a great answer, but it goes a little out of scope. You should feel good about yourself too for the next couple of days!
      singulars
      1. PO
      1. USBreedly
    2. CO@Breedly: I have just started feeling good about myself ;) Seriously, since you are a newbee to C++ then why not start the right way? And since you want to implement your ownr array, I think it is the best and safest way too. Have fun with C++.
      singulars
      1. PO
      1. USGrzegorz
    3. CO@Grzegorz Nice things to teach, but maybe too early. Now that you have shown that he needs a Destructor, you probably need to talk about the Rule of Three, otherwise it will not be "the best and safest way".
      singulars
      1. PO
      1. USAlex Oliveira
 

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