Databases
StackOverflow2013
Postsdbo
POCalling class method without using the object?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POCalling class method without using the object?
    primarykey
    data
    text
    <p>This might seem like a silly question to the more seasoned C++ coders out there, but I thought once you have a class and you create an object of that class, you call a public method of that class using the object you created (unless it is a static method, in which case you call it either using an object or the class name itself)?</p> <p>Then why does this work?</p> <p>Function definition:</p> <pre><code>template &lt;typename Object&gt; void printList(const List&lt;Object&gt;&amp; theList) { if (theList.isEmpty()) cout &lt;&lt; "Empty list!" &lt;&lt; endl; else { ListItr&lt;Object&gt; itr = theList.first(); for(; !itr.isPastEnd(); itr.advance()) cout &lt;&lt; itr.retrieve() &lt;&lt; " "; } cout &lt;&lt; endl; } </code></pre> <p>Function call:</p> <pre><code>printList(myList); </code></pre> <p>What am I missing here? How does the rest of the program know that <code>printList()</code> belongs to the class <code>List&lt;int&gt;</code> unless I call <code>printList()</code> using an object of <code>List&lt;int&gt;</code>?</p> <p>This works too by the way, I just checked. I would have used this way of calling and defining the function. Note that this time the function is defined using the <code>this</code> pointer, the way I would have thought it works.</p> <p>Function definition:</p> <pre><code>template &lt;typename Object&gt; void List&lt;Object&gt;::printList() { if(this-&gt;isEmpty()) cout &lt;&lt; "Empty list!" &lt;&lt; endl; else { ListItr&lt;Object&gt; itr = this-&gt;first(); for(; !itr.isPastEnd(); itr.advance()) cout &lt;&lt; itr.retrieve() &lt;&lt; " "; } cout &lt;&lt; endl; } </code></pre> <p>Function call:</p> <pre><code>myList.printList(); </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USLightness Races in Orbit
    1. USAmbidextrous
    plurals
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. CO`How does the rest of the program know that printList() belongs to the class List<int>` Does it? Why does it take a `List<int>` as a parameter, then? Looks to me like you created a free function, not a member function... especially since when you _do_ create a member function in your second example, your show with your usage of `List<Object>::` that you're doing these function definitions outside of a class definition.
      singulars
      1. POCalling class method without using the object?
      1. USLightness Races in Orbit
    2. COBecause ... that's *not* a method in a class. It's a simple function.
      singulars
      1. POCalling class method without using the object?
      1. USBrian Roach
    3. COThanks - I fixed that and made the first one a member function; and now it needs the object to be able to be called. Still seems strange why it needs the object also passed as a parameter when the same can be done with using 'this'.
      singulars
      1. POCalling class method without using the object?
      1. USAmbidextrous
 

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