# createHashMap

## Category
HashMap

## Arity
**Nular** — `createHashMap`.

```
createHashMap
```

## Description
Creates a new empty hashmap (dictionary). HashMaps store key-value pairs with fast O(1) lookup. Keys and values can be of any type. Keys are compared by value — two equal numbers or strings are considered the same key.

## How It Works
Allocates a new `Dictionary<Value, Value>` with the SQ# equality comparer. The hashmap is mutable and owned by the current scheduler.

## Usage

### Create and populate
```sqf
_map = createHashMap;
_map set ["health", 100];
_map set ["name", "player"];
_map set ["alive", true];
```

### Read values
```sqf
_hp = _map get "health";       // 100
_name = _map get "name";       // "player"
_missing = _map get "xyz";     // nil (key not found)
```

### Check key existence
```sqf
if (!isNil {_map get "health"}) then {
    systemChat f"Health: {_map get "health"}";
};
```

### As configuration store
```sqf
_config = createHashMap;
_config set ["maxPlayers", 32];
_config set ["difficulty", "hard"];
_config set ["timeLimit", 900];
```

### Nested maps
```sqf
_player = createHashMap;
_player set ["name", "John"];
_stats = createHashMap;
_stats set ["hp", 100];
_stats set ["xp", 500];
_player set ["stats", _stats];
```

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

## See Also
- [createHashMapFromArray](createHashMapFromArray.md) — create from key-value array
- [get](get.md) — retrieve value by key
- [set](set.md) — store key-value pair