# Map

Operators and functions for working with map arrays (**map** type) are described here. **map.typename** means that you can specify any type name but in the case of the binary operator this type must be the same in both maps.

* [bool( map.typename m ) bool](/stdlib/map.md#bool-map-typename-m-bool)
* [Del( map.typename m, str key ) map.typename](/stdlib/map.md#del-map-typename-m-str-key-map-typename)
* [IsKey( map.typename m, str key ) bool](/stdlib/map.md#iskey-map-typename-m-str-key-bool)
* [Key( map.typename m, int index ) str](/stdlib/map.md#key-map-typename-m-int-index-str)

## Operators

| Operator                         | Result       | Description                                                                    |
| -------------------------------- | ------------ | ------------------------------------------------------------------------------ |
| **\*** map.typename              | int          | Returns the number of elements in the map.                                     |
| map.typename **?**               | bool         | Calls *bool(map.typename)*.                                                    |
| map.typename **=** map.typename  | map.typename | Assignment operator.                                                           |
| map.typename **&=** map.typename | map.typename | Creates a clone of the map. The new variable will work with the same data set. |
| map.typename **\[** str **]**    | typename     | Sets/gets a map value by key.                                                  |

## Functions

### bool(map.typename m) bool

The *bool* function returns *false* if the map is empty, otherwise, it returns *true*.

### Del( map.typename m, str key ) map.typename

The *Del* function deletes the specified key and its value from the *map* array. The *m* parameter is returned.

### IsKey( map.typename m, str key ) bool

The *IsKey* function returns *true* if there is a value with the specified key in the *map* and *false*, otherwise.

### Key( map.typename m, int index ) str

The *Key* function returns the item key by its index. For example, this function can be used in the *for* loop to get the item key.

```go
for val,i in mymap {
    Println("\(Key(mymap, i)):\(val)")
}
```


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