Code Conventions

Code conventions

Here you find conventions about how the VLC media player 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: intf_FooFunction. Static functions don't need the module name.

Variable naming

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

• i_ for integers (sometimes l_ for long integers)
• b_ for booleans
• d_ for doubles
• f_ for floats
• Generally, we add a p when the variable is a pointer to a type
  • pf_ for function pointers
  • psz_ 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 p_ 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:

• data_packet_t * p_buffer
• char psz_msg_date[42]
• int pi_es_refcount[MAX_ES];
• void (* pf_next_data_packet)( int * )

Macro usage

Static inline is preferred over macros, for example:

 static inline void change_val(int * var, int val)
 {
     *var = val;
 }

is preferred to

 #define CHANGE_VAL(var_name, val) var_name = val;

A few words about white space

Indentation

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

Use set expandtab under vim or the equivalent under emacs.

Indents are 4 spaces long.

Spaces

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

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

Braces

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

if( i_es == 42 )
{
   p_buffer[0] = 0x12;
}

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 HACKING