C++ Development Standards

1. Intro

Why do we need coding standards?

It makes easier to maintain and read all the scripts related code and gives us more control over the code.

In some cases it will be a safe guard against errors.

Why is it important for occasional developers/contributors?

We only accept code that is written according to our developing standards.

A properly written patch goes faster to core than unordered ones and makes the maintainers lifes easier.

2. Coding Standards

Tab size / Indents

Code never contain tabs, instead we use spaces.
By tab size, we mean 4x spaces. Not 5, not 3.
Most sane development-tools have options to replace tabs with 4 spaces.

Visual Studio:
Tools -> Options: Text Editor -> C++ -> Tabs

Smart, 4, 4, Insert spaces.

Notepad++:
Settings -> Preferences -> Language

Tab size: 4, Replace by space: checked

Comments

Always comment code where it is not typical code repeated in many/all scripts and/or not self-explanatory what the code does.
A comment should either be placed directly above the code :

// My comment
if (something == MY_CONSTANT)

or at code line 61 if this fits more natural in the code :

if (something == MY_CONSTANT)
{
	a = b; // My comment

Whitespace

Do not file source code containing white space in end of line. Generally a no-no.
Do not fill parenthesis with whitespace. Place space in front, not after.

Wrong :

if( attack )
if ( attack )

Correct :

if (attack)

Brackets

We use symmetric brackets. One line blocks does not need brackets

if (attack)
{
	me->DoA();
	me->DoB();
}
else
{
	me->SelectA(); me->SelectB();
}

or

if (attack)
{
	me->DoA();
	me->DoB();
}
else
	me->SelectA();

Loop syntax

Similar to if () blocks, one line statements do not need brackets

for (uint32 i = 0; i < loopEnd; ++i)
{
	DoSomething();
	DoSomethingElse();
}
 
uint32 i = 0;
while (i < 10)
{
	DoSomething();
	DoSomethingElse();
	++i;
}
 
do
{
	DoSomething();
	DoSomethingElse();
	--i;
}
while (i > 0);

Magic numbers vs. Constants

Constants makes code easier to read and does also provide a degree of fail safe.
Wrong :

if (player->GetQuestStatus(10090) == 1)
	me->RemoveFlag(58, 2);

Correct :

if (player->GetQuestStatus(QUEST_BEAT_UP) == QUEST_STATUS_INCOMPLETE)
	me->RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);

Constants are either set as #define, or most preferred in a enum. If it does not exist, make one.

Enumeration vs. define

It is strongly advised to avoid using #defines for constants, use either a const variable or an enum, if multiple variables can be grouped together
Enums must have a name. Separate constant on different enums depending on their type.
Correct :

enum Spells
{
	SPELL_1 = 23444,
	SPELL_2 = 23233,
	H_SPELL_3 = 28345
};

Standard constant name prefixes

Constant names have standardized prefixes :

Quote

SPELL_ : Spell id
NPC_ : Creature_template.entry
ITEM_ : Item_template.entry
GO_ : Gameobject_template.entry
QUEST_ : Quest_template.entry
SAY_ : Script_texts.entry (yell/normal say)
EMOTE_ : Same as above, just different prefix to clearly see its emote
EQUIP_ : Typically a item id(id from dbc, not _template)
MODEL_ : A creature model
H_XX : Heroic mode prefix (goes before the other prefix) XX is max man amount from mode. (OBSOLETE AS OF PATCH 3.2 WITH SpellDifficulty.dbc)
RAID_XX : Raid mode prefix (goes before the other prefix) XX is max man amount from mode. (OBSOLETE AS OF PATCH 3.2 WITH SpellDifficulty.dbc)
EVENT_ : Event/Encounter identifier for instances
DATA_ : Identifiers in instance used for GUIDs/data not being event/encounter
ACHIEV_ : Achievement id

Correct :

SPELL_ENRAGE 
H_XX_SPELL_ENRAGE 
EVENT_ILLIDAN 
DATA_ILLIDAN 
ACHIEV_OH_NOVOS

Naming of variables and functions

No matter what, DO NOT USE HUNGARIAN NOTATION IN VARIABLE NAMES

for public/protected members or global variables: