Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p><strong>Declaration</strong></p> <p>A prototype for a function which takes a function parameter looks like the following:</p> <pre><code>void func ( void (*f)(int) ); </code></pre> <p>This states that the parameter <code>f</code> will be a pointer to a function which has a <code>void</code> return type and which takes a single <code>int</code> parameter. The following function (<code>print</code>) is an example of a function which could be passed to <code>func</code> as a parameter because it is the proper type:</p> <pre><code>void print ( int x ) { printf("%d\n", x); } </code></pre> <p><strong>Function Call</strong></p> <p>When calling a function with a function parameter, the value passed must be a pointer to a function. Use the function's name (without parentheses) for this:</p> <pre><code>func(print); </code></pre> <p>would call <code>func</code>, passing the print function to it.</p> <p><strong>Function Body</strong></p> <p>As with any parameter, func can now use the parameter's name in the function body to access the value of the parameter. Let's say that func will apply the function it is passed to the numbers 0-4. Consider, first, what the loop would look like to call print directly:</p> <pre><code>for ( int ctr = 0 ; ctr &lt; 5 ; ctr++ ) { print(ctr); } </code></pre> <p>Since <code>func</code>'s parameter declaration says that <code>f</code> is the name for a pointer to the desired function, we recall first that if <code>f</code> is a pointer then <code>*f</code> is the thing that <code>f</code> points to (i.e. the function <code>print</code> in this case). As a result, just replace every occurrence of print in the loop above with <code>*f</code>:</p> <pre><code>void func ( void (*f)(int) ) { for ( int ctr = 0 ; ctr &lt; 5 ; ctr++ ) { (*f)(ctr); } } </code></pre> <p>From <a href="http://math.hws.edu/bridgeman/courses/331/f05/handouts/c-c++-notes.html" rel="noreferrer">http://math.hws.edu/bridgeman/courses/331/f05/handouts/c-c++-notes.html</a></p>
    singulars
    1. This table or related slice is empty.
    1. POHow do you pass a function as a parameter in C?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USandrewrk
    1. USNiyaz
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POHow do you pass a function as a parameter in C?
      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. COIn your first and last code examples, the * is not compulsory. Both the function parameter definition and the `f` function call can take `f` just as is without *. It might be a good idea to do it as you do though, to make it obvious that parameter f is a function pointer. But it hurts readability quite often.
      singulars
      1. PO
      1. USGauthier
    2. COSee [c99, 6.9.1§14] for examples. Both are correct of course, I just wanted to mention the alternative.
      singulars
      1. PO
      1. USGauthier
 

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