Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Generally, a header file notifies the <em>compiler</em> of certain things (mostly their existence or declarations) so that the compiler can correctly build a single translation unit (such as a single C file).</p> <p>A library file is the actual <em>executable code</em> that does the work as specified in that header file. This is linked in by the <em>linker</em> to provide the actual functionality (the _definitions rather than just the declarations).</p> <p>So, in your example, you may have the line:</p> <pre><code>#include &lt;pthread.h&gt; </code></pre> <p>which tells the compiler all about the <em>existence</em> of the <code>pthread_mutex_this</code>, <code>pthread_condvar_that</code> and <code>pthread_thread_the_other</code> stuff but doesn't actually provide the implementations of those things.</p> <p>The <code>-lpthread</code> option tells the linker that it should locate a library based on the <code>pthread</code> name from which it can pull in the actual implementations, in order to forn the final executable.</p> <p>Similarly, while <code>stdio.h</code> holds information about the I/O stuff, the actual code for it will be in the runtime library (though you rarely have to link that library specifically since the compiler will try to take care of it for you). Because you usually link with the compiler (i.e., the compiler invokes the linker for you), it knows that you're probably going to need the C run time library. If you were to use the linker directly (such as by using the <code>ld</code> command), that probably wouldn't happen, and you'd have to be explicit.</p>
    singulars
    1. This table or related slice is empty.
    1. POWhat are Header Files and Library Files?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USpaxdiablo
    1. USpaxdiablo
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POWhat are Header Files and Library Files?
      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. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    1. COthank you paxdiablo but a small question why we include -lpthread in command line when we use posix threads but why not for the other header files like stdio.h math.h why dont we say -lmath or -lstdio ??any good reason
      singulars
      1. PO
      1. USkarthik
    2. COActually, @karthik, you _do_ sometimes have to specify `-lmath` (for those environments where they have it separate from the C RTL). But the reason why you don't normally have to do it is explained in the last paragraph of my answer - I'll expand on that a bit.
      singulars
      1. PO
      1. USpaxdiablo
    3. CO@karthik Most standard C and posix functions are in the standard C library, which is linked in by default, while others (such as pthread function or some of the math functions) reside in other libraries which have to be linked in explicittly.
      singulars
      1. PO
      1. USnos
 

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