Scripting in ArmA is changed somewhat from OFP times.

In OFP we have the SQS scripts which are read line by line, in ArmA now we have the SQF scripts which are read like a code. They are so much more powerful and easier to use once you get the idea, do not be afraid of them even if you've mastered the SQS method before but now the SQF things look strange and scary. Trust me on this, learn it and you'll be amazed how great SQF scripting is.

In a nutshell you never ever should create ArmA SQS content anymore, always create only SQF scripts.

How do you run SQF script?

argument execVM filename

Example:

var = [player] execVM "test.sqf";

Argument is passed to the script as local variable _this. The Script is first searched for in the mission folder, then in the campaign scripts folder and finally in the global scripts folder.

ArmA has “” quotes for STRINGS only and {} curled braces for CODE only. Script commands doesn’t have to be in one line now with the curled braces. Command lines always end with ; instead of a ; *or* carriage return. So you can format code to be more readable

{
    if (condition) then
    {
        DoSomething1;
        DoSomething2;
        DoSomething3;
        DoSomething4;
        DoSomething5;
     };
} forEach array;

Instead of the terrible ofp classic

{if (condition) then {DoSomething1; DoSomething2; DoSomething3; DoSomething4; DoSomething5;};} foreach array;

Comments are no longer the same character as the end of command character.

// my comment
instead of
; my comment

You can use block comments now.

/*
Comment line 1
Comment line 2
Comment line 3
Comment line 4
Comment line 5
Comment line 6
*/

Quotes are no longer a valid substitute for braces.

Some misc SQF things here ;)

_resultArray = [0,""];
_handle = [_resultArray] execVM "resultScript.sqf";
// script runs and changes the _resultArray that is was given
waitUntil {scriptDone _handle};
_resultInt = _resultArray select 0;
_resultString = _resultArray select 1;

And

myFunction1 = compile loadFile "myFunction1.sqf";
myFunction2 = compile preprocessFile "myFunction2.sqf";

call myFunction1;
[1, 2] call myFunction2;

Return value?

value = call compile preprocessFile "return.sqf";
// value is now RETURN_VALUE

call compile preprocessFile "return.sqf";
// valid, but RETURN_VALUE is not saved anywhere

Using the private list.

private ["_t","_p","_yea"];

Is to make the _local variables really a private ones in the SQF script.

if (condition) exitWith {Code}

if (_x > 5) exitWith {echo "_x is too big"; _x}

and

for "_j" from 1 to 10 do
{
	player sideChat format ["%1",_j];
	if (_j == 5) exitWith {player sideChat "5 is enough"};
};
player sideChat "Complete";

Switch is quite nice option to check many conditions at once.

Example 1

switch (_a) do
{
	case 1:
	{
		hint "1";
	};
	case 2:
	{
		hint "2";
	};
	default
	{
		hint "default";
	};
;}

Example 2

switch (_a) do
{
	case true:
	{
		hint "true";
	};
	case false:
	{
		hint "false";
	};
	default
	{
		hint "default";
	};
};

Example 3

switch (_a) do
{
	case "string1":
	{
		hint "string1";
	};
	case "string2":
	{
		hint "string2";
	};
	default
	{
		hint "default";
	};
};

When you have script like this

MyScript = compile preProcessFile "myScript.sqf";

When you want to unload the script, set MyScript equal to nil.

MyScript = nil;

Dynamic variables are very cool, sometimes on those random/comples missions you want to make variables later in the mission, which you cannot specify at mission start (hardcode).

_MyVariable = 20;
_MyVariableContent = "MyContent";
call compile format["MyDynamic_%1=_MyVariableContent",_MyVariable];

This would create: MyDynamic_20 variable with content: “MyContent”

Another example

_name = format ["mytrigger%1", triggerIndex];
call compile format ["%1 = createTrigger [....]", _name];

Place random vehicles + some units on all found pmc_ gamelogics script, here.