Ruby have great documentation for Array method for example like this. To day I want to focus not on methods in documentation but some tips I know in Ruby with Array. Let’s start:

- Create Array with strings:

```
%w{ 1 2 3 4 }
=> ["1", "2", "3", "4"]
```

- Create Array with the same number:

```
[2]*5
=> [2, 2, 2, 2, 2]
```

- Create Array with ordered numbers:

```
(1..4).to_a
=> [1, 2, 3, 4]
```

- Create Array with even numbers:

```
(2..10).step(2).to_a
=> [2, 4, 6, 8, 10]
```

- Show last element in Array:

```
array = [1, 2, 3, 4]
array[-1]
=> 4
```

- Show part of Array:

```
array = [1, 2, 3, 4]
array[1..2]
=> [2, 3]
array[1...3]
=> [2, 3]
array[1, 2]
=> [2, 3]
```

- Array decomposition:

```
a, b, c = [1, 2, 3, 4]
a => 1
b => 2
c => 3
```

or

```
a, b, *c = [1, 2, 3, 4]
a => 1
b => 2
c => [3, 4]
```

- Sum all elements in Array (
`inject`

and`reduce`

methods are aliases):

```
array = [1, 2, 3, 4]
array.inject(&:+)
=> 10
```

or

```
array.reduce(&:+)
=> 10
```

- Removed specific elements from Array:

```
array = [1, 2, 3, 4]
array.slice!(1..2)
array => [1, 4]
```

- Array operations:

```
# Sum
[1, 2, 3] | [1, 4] => [1, 2, 3, 4]
# Concatenation
[1, 2, 3] + [1, 4] => [1, 2, 3, 1, 4]
# Product
[1, 2, 3] & [1, 4] => [1]
# Difference
[1, 2, 3] - [1, 4] => [2, 3]
```