Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>a class declaration is where you declare the class hence. or as </p> <blockquote> <p>From the C++ standard section 3.1:</p> <p>A declaration introduces names into a translation unit or redeclares names introduced by previous declarations. A declaration specifies the interpretation and attributes of these names.</p> </blockquote> <p>In essence the declaration tells the compiler a certain object, variable, etc with a certain name exists. There can be multiple declartions in a compile unit </p> <p>so in a way </p> <pre><code>class X; // is declaration also known as forward declaration. </code></pre> <p>Is just a declaration. However there must always be just one and only one definition for each object / variable. And a definition is basically everything the compiler needs in order to create an instance of that class / object / struct / variable etc.</p> <p>In c++ many times a class declaration can also be a definition or partial definition/</p> <pre><code>//declare a class and declare it's members. class X { //declares X and starts to define it void test (); //declare test method int b; // declare b member } </code></pre> <p>the full definition can then be in a .cpp file like this:</p> <pre><code>void X::test() { //test code } </code></pre> <p>or in the class declration like this:</p> <pre><code> class X { void test () { //test code } </code></pre> <p>Here is an extensive stackoverflow discussion on the differences:</p> <p><strong><a href="https://stackoverflow.com/questions/1410563/what-is-the-difference-between-a-definition-and-a-declaration">What is the difference between a definition and a declaration?</a></strong></p> <p>I believe the author is recommending that you do not use the second type of declaration in which you declare and define the methods inside the class definition but in a separate c++ file. This is because of the C++ define only once rule, you do not want to include the same .h file from multiple files and have multiple definitions for the same class.</p> <p>Here is another extensive discussion on why you should seperate:</p> <p><strong><a href="https://stackoverflow.com/questions/4955159/is-is-a-good-practice-to-put-the-declaration-of-c-classes-into-the-header-file">Is is a good practice to put the definition of C++ classes into the header file?</a></strong></p>
    singulars
    1. This table or related slice is empty.
    1. POclass definition and class declaration
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USCommunity
    1. USDory Zidon
    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. VTDownMod
    1. COsorry,not me,thanks for answer
      singulars
      1. PO
      1. USbooirror
    2. COI didn't downvote, but the definition of the member functions isn't part of the definition of a class. The function body may appear inside the class definition, but that doesn't make it part of what is required to define a class.
      singulars
      1. PO
      1. USdyp
    3. COI agree, declaring something means you have all the info to create it..so in essence you do not need the declaration of the methods to create the class instance..however, many times when putting all of them in the same place, and not splitting into header and cpp you get issues :)
      singulars
      1. PO
      1. USDory Zidon
 

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