arrays.md

version	example_title
1.0.0	Arrays

Arrays

An array is a collection of items stored in contiguous memory locations. It's an aggregate data structure that is designed to store a group of objects of the same type. It's the most efficient data structure for storing and accessing a sequence of objects.

How to declare an array

Create an array that holds integer values:

mut ages := [18, 25, 37]

println(ages)

Output

[18, 25, 37]

Or create an array that holds string values:

mut users := ['vbrazo', 'donnisnoni95', 'Delta456']

println(users)

Output

['vbrazo', 'donnisnoni95', 'Delta456']

Note: All elements must have the same type. The following code will not compile.

mut users := ['vbrazo', 'donnisnoni95', 'Delta456', 0]

Output

~/main.v:2:43: bad array element type `int` instead of `string`

Create an empty array

If you want to create a new empty array, just declare [] followed by the data type.

mut names := []string
mut numbers := []int

Accessing element of the array

mut users := ['vbrazo', 'donnisnoni95', 'Delta456']

println(users[0])
println(users[2])
println(users[1])

Output

vbrazo
Delta456
donnisnoni95

Append a value to an array

<< is an operator that appends a value to the end of the array.

mut ages := [18]
ages << 47

println(ages)

Output

[18, 47]

It can also append an entire array.

mut ages := [18]
ages << [47, 49]

println(ages)

Output

[18, 47, 49]

Length/size of an array

.len method returns the length of the array.

mut names := ['Thiago', 'John']

println(names.len)

Output

2

In operator

in check if an element is inside an array.

mut names := ['Thiago', 'Alex', 'Joe']

println('Vitor' in names)
println('Thiago' in names)

Output

false
true

Slicing an array

It's easy to slice an array in V. You can slice an array with the default V slicing feature without having to call the slice () method. The syntax is like this my_array[start..end]

animals := ['lion', 'goose', 'chicken', 'turkey', 'tiger']
poultry := animals[1..4]
println(poultry) // ["goose", "chicken", "turkey"]

If you want to slice from the start of the index, just ignore it to put 0 and using instead my_array[..end] or my_array[start..].

x := ['h', 'e', 'l', 'l', 'o']
y := x[..x.len-1]
z := x[1..]
println(y) // ['h', 'e', 'l', 'l']
println(z) // ['e', 'l', 'l', '0']

Exercises

1. Write a V program to store elements in an array and print it.
2. Write a V program to read n number of values in an array and display it in reverse order.
3. Write a V program to find the sum of all elements of the array.
4. Write a V program to copy the elements of one array into another array.
5. Write a V program to count a total number of duplicate elements in an array.