# append

## Category
Array

## Arity
**Binary** — `<array> append <otherArray>`.

```
<array> append <array>
```

## Description
Appends all elements from the right-hand array into the left-hand array. This is a bulk operation — more efficient than repeated `pushBack` calls. No return value (void).

## How It Works
Calls `List<Value>.AddRange()` on the underlying list. All elements from the source array are added in order. The source array is not modified.

## Usage

### Merge arrays
```sqf
_arr1 = [1, 2, 3];
_arr2 = [4, 5, 6];
_arr1 append _arr2;            // _arr1 is [1,2,3,4,5,6]
```

### Collecting results
```sqf
_allUnits = [];
_allUnits append _infantry;
_allUnits append _vehicles;
_allUnits append _air;
```

### Array concatenation helper
```sqf
_concat = {
    params ["_a", "_b"];
    _result = [];
    _result append _a;
    _result append _b;
    _result
};
_combined = [_arr1, _arr2] call _concat;
```

### vs pushBack
```sqf
// Bad — many individual pushes
{ _target pushBack _x } forEach _source;

// Good — single bulk append
_target append _source;
```

## Thread Safety
**Not thread-safe**. Both arrays must belong to the current scheduler.

## See Also
- [pushBack](pushBack.md) — append single element
- [deleteRange](deleteRange.md) — remove range of elements
- [resize](resize.md) — change array size
- [select](select.md) — element access