Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Jonathan, you beat me to an answer, but this may be helpful as well. Here, <code>api.c</code> contains the (private) implementation, and <code>api.h</code> provides the interface to be consumed by other code such as <code>main.c</code>.</p> <pre><code>// main.c: uses only the public interface to the private code #include "api.h" int main(int argc, char *argv[]) { void *foo; foo = create_foo("five", 5); print_foo(foo); delete_foo(foo); } // EOF main.c </code></pre> <p><br></p> <pre><code>// api.h: the public interface #ifndef _api_h_ #define _api_h_ void *create_foo(char *name, int number); void print_foo(void *foo); void delete_foo(void *foo); #endif // _api_h_ </code></pre> <p><br></p> <pre><code>// api.c: the private implementation #include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; #include &lt;string.h&gt; // The real structure is private to the implementation. typedef struct { char name[20]; int number; } real_struct; // Create a new structure, initialize, return as ptr-to-void. void *create_foo(char *name, int number) { real_struct *s = malloc(sizeof(real_struct)); strcpy(s-&gt;name, name); s-&gt;number = number; return (void *) s; } // Print the data. void print_foo(void *foo) { real_struct *s = (real_struct *) foo; printf("name: %s, number: %d\n", s-&gt;name, s-&gt;number); } // Release the memory. void delete_foo(void *foo) { free(foo); } // EOF api.c </code></pre> <p>This code should compile and run:</p> <pre><code>$ gcc -o foo main.c api.c $ ./foo name: five, number: 5 </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POTypecasting (or deference) void * to struct foo*
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. USAdam Liss
    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. This table or related slice is empty.
    1. COI'm going to nit-pick because I'm good at nit-picking (though it's only a small nit-pick). You should not use `_api_h_` as the header guard; names starting with an underscore are reserved for the implementation. See §7.1.3 Reserved Identifiers in the C99 standard, bullet 2: _All identifiers that begin with an underscore are always reserved for use as identifiers with file scope in both the ordinary and tag name spaces._ Your choice of `_api_h_` therefore can run foul of the system's names. If you used `api_h_` or something else like that, no argument.
      singulars
      1. PO
      1. USJonathan Leffler
    2. CO@JonathanLeffler: +1 for keeping me honest. It's been a long time since I've written "real" C code, and old habits die hard. Keep nit-picking. I'll learn. :-)
      singulars
      1. PO
      1. USAdam Liss
 

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