count

Notes from before the conversion:

Use this to calculate how many "M16" mags a soldier has left.

{ _x == "M16" } count magazines soldier1;

Take care when using count to determine how many units are left alive in a group: count units group player or count units groupname Will return the number of units the leader of the group thinks are alive. If some units have been killed out of sight of other members of the group then it may take sometime for this to be the actual numbers in the group. To determine exactly how many units are really alive in a group use:

{ alive _x } count units group player;

or

{ alive _x } count units groupname;

count can be (ab)used for a very fast and simple check if at least one element in an array fulfills a certain condition:

if ({ if (/* _x fulfills condition */) exitWith {1}; false } count _array isEqualTo 1) then
{
    // do whatever here
};

This code will exit the count loop as soon as it finds an element fulfilling the condition, leaving the count with the value of 1, hence make the larger if-condition be true.

If no array element fulfills the condition, the count will be 0 and the if-condition will be false.

Quit loop at first fulfilled condition (same as above but faster):

{
    if (_x == 4) exitWith {
        // do something when we reach 4
    }
} count [1,2,3,4,5,6];

Using exitWith inside a count loop will overwrite the default functionality and make count return whatever the exitWith returns:

_result = {
    if (_x isEqualTo 3) exitWith { "Hello" }
} count [1,2,3,4,5];
// _result = "Hello"

With the alternative syntax each iteration should result in an interior return of bool or nothing. Example:

createDialog "RscFunctionsViewer";
{ lbAdd [292901, _x]; } count ["first", "second", "third"];

lbAdd returns a number, so this throws "Error Type Number, expected Bool". Tested in A2OA 1.63.131129