View source for Code Conventions

== Code conventions ==
Here you find conventions about how the {{VLC}} developers write their code.

=== Function naming ===

All functions are named accordingly: ''module name'' (in lower case) + _ + ''function name'' (in mixed case, without underscores). For instance: <tt>intf_FooFunction</tt>. Static functions don't need the module name.

=== Variable naming ===

We use Hungarian notation. That is, we have the following prefixes:

*<tt>i_</tt> for integers (sometimes <tt>l_</tt> for long integers)
*<tt>b_</tt> for booleans
*<tt>d_</tt> for doubles
*<tt>f_</tt> for floats
*Generally, we add a <tt>p</tt> when the variable is a pointer to a type
**<tt>pf_</tt> for function pointers
**<tt>psz_</tt> for a pointer to a string terminated by a zero (C-string)

If a variable has no basic type (for instance a complex structure), don't put any prefix (except <tt>p_</tt> if it's a pointer). After one prefix, put an explicit variable name in lower case. If several words are required, join them with an underscore (no mixed case).

Examples:

*<tt>data_packet_t * p_buffer</tt>
*<tt>char psz_msg_date[42]</tt>
*<tt>int pi_es_refcount[MAX_ES];</tt>
*<tt>void (* pf_next_data_packet)( int * )</tt>

=== Macro usage ===

Static inline is preferred over macros, for example:

<code>
  static inline void change_val(int * var, int val)
  {
      *var = val;
  }
</code>
is preferred to
<code>
  #define CHANGE_VAL(var_name, val) var_name = val;
</code>

=== A few words about white space ===
==== Indentation ====

'''Never''' use tabs in the source (nevertheless you're entitled to use them in the Makefile :-). 

Use <tt>set expandtab</tt> under vim or the equivalent under emacs.

Indents are 4 spaces long.

==== Spaces ====

Put spaces before and after operators, and inside brackets. For instance:

<code>
 for( i = 0; i < 12; i++, j += 42 ); 
</code>

==== Braces ====

Leave braces alone on their lines (GNU style). For instance:

<code>
 if( i_es == 42 )
 {
    p_buffer[0] = 0x12;
 }
</code>

=== Comments ===
        
ANSI C-style comments /* ... */ are more commonly used for historical reasons, though C++/C99 comments are tolerated, but please don't mix both in the same file.

== Qt interface added conventions ==
'''''See [http://trac.videolan.org/vlc/browser/modules/gui/qt4/HACKING HACKING]'''''

[[Category:Coding]]