# Array

Operators and functions for working with arrays (**arr** type) are described here. **arr.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 arrays.

* [bool( arr.typename a ) bool](/stdlib/array.md#bool-arr-typename-a-bool)
* [Join( arr.str a, str sep ) str](/stdlib/array.md#join-arr-str-a-str-sep-str)
* [Reverse( arr.typename a ) arr.typename](/stdlib/array.md#reverse-arr-typename-a-arr-typename)
* [Slice( arr.typename a, int start, int end ) arr.typename](/stdlib/array.md#slice-arr-typename-a-int-start-int-end-arr-typename)
* [Sort( arr.str a ) arr.str](/stdlib/array.md#sort-arr-str-a-arr-str)

## Operators

| Operator                             | Result           | Description                                                                      |
| ------------------------------------ | ---------------- | -------------------------------------------------------------------------------- |
| **\*** arr.typename                  | int              | Returns the number of elements in the array.                                     |
| arr.typename **?**                   | bool             | Calls *bool(arr.typename)*.                                                      |
| arr.typename **=** arr.typename      | arr.typename     | Assignment operator.                                                             |
| arr.typename **&=** arr.typename     | arr.typename     | Creates a clone of the array. The new variable will work with the same data set. |
| arr.typename **+=** arr.typename     | arr.typename     | Adds items from one array to another.                                            |
| arr.str **+=** str                   | arr.str          | Adds a string to an array of strings.                                            |
| arr.int **+=** int                   | arr.int          | Adds an integer number to an array of integer numbers.                           |
| arr.bool **+=** bool                 | arr.bool         | Adds a Boolean value to an array of Boolean values.                              |
| arr.arr.typename **+=** arr.typename | arr.arr.typename | Adds an array to an array of arrays.                                             |
| arr.map.typename **+=** map.typename | arr.map.typename | Adds a map to an array of maps.                                                  |
| arr.typename **\[** int **]**        | typename         | Sets/gets an array value by index.                                               |

## Functions

### bool(arr.typename a) bool

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

### Join(arr.str a, str sep) str

The *Join* function joins strings of the array. The separator string *sep* is placed between strings in the resulting string.

### Reverse( arr.typename a ) arr.typename

The *Reverse* function reverses the order of the elements in the array and returns this array.

### Slice( arr.typename a, int start, int end ) arr.typename

The *Slice* function copies some consecutive elements from within an array. *start* is inclusive, while *end* is exclusive. The function returns the created array.

### Sort(arr.str a) arr.str

The *Sort* function sorts an array of strings in increasing order and returns it.


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