# pushBack

## Category
Array

## Arity
**Binary** — `<array> pushBack <element>`.

```
<array> pushBack <any>
```

## Description
Appends a single element to the end of the array. Returns the index at which the element was inserted (the new last index). This matches Arma SQF `pushBack` behavior.

**Thread Safety**: Not thread-safe. Array must belong to current scheduler.

## How It Works
Adds the element to the underlying `List<Value>`, then returns `Count - 1` (the index of the newly added element). The array grows by 1.

## Usage

### Basic push
```sqf
_arr = [1, 2, 3];
_idx = _arr pushBack 4;        // returns 3, _arr is [1,2,3,4]
_arr pushBack 5;               // _arr is [1,2,3,4,5]
```

### Building arrays dynamically
```sqf
_enemies = [];
{
    if (_x get "side" == "east") then {
        _enemies pushBack _x;
    };
} forEach _allUnits;
```

### Ignore return value
```sqf
_queue pushBack _newTask;      // just append, don't need index
```

### Chain with return
```sqf
_arr = [];
_lastIdx = _arr pushBack "first";   // 0
_lastIdx = _arr pushBack "second";  // 1
```

## Thread Safety
**Not thread-safe**. Array must be owned by the current scheduler. Use [freeze](freeze.md) for cross-scheduler sharing, or [sendTo](sendTo.md) to transfer ownership.

## See Also
- [append](append.md) — append many elements at once
- [deleteAt](deleteAt.md) — remove element
- [select](select.md) — access element
- [count](count.md) — array length
- [resize](resize.md) — change array size