# Maps

Maps are a built-in associative data-structure in golang that allows us to store data in key-value pairs. Maps are synonymous to hashes or dicts in other languages. Below, we will go over some of the basics of maps in golang

#### Creating a new map

To create a new map, we use the `make` keyword

{% code lineNumbers="true" %}

```go
package main
import "fmt"

func main() {
  vending_machine := make(map[string]int)
  vending_machine["coke"] = 9
  vending_machine["beer"] = 3
  vending_machine["water"] = 24
  fmt.Println("number of items: ", len(vending_machine")
  fmt.Println("vending machine items", vending_machine)
  
  // we can also declare and init a map as follows
  inventory := map[string]int{"pepsi": 10, "sprite": 4, "rootbeer": 1}
  fmt.Println("inventory: ", inventory)
}
```

{% endcode %}

#### Get, update, delete, items in maps

We can add, delete, and change values of items in a map

{% code lineNumbers="true" %}

```go
package main
import "fmt"

func main() {
  vending_machine := make(map[string]int)
  vending_machine["coke"] = 9
  vending_machine["beer"] = 3
  vending_machine["water"] = 24
  fmt.Println("number of items: ", len(vending_machine")
  fmt.Println("vending machine items", vending_machine)
  
  coke_price := m["coke"]
  fmt.Println("number of coke bottles: ", coke_price)
  
  // the built-in method, delete removes the item from the map
  delete(vending_machine, "water")
  fmt.Println("vending machine ran out of water:", vending_machine)
  fmt.Println(len(vending_machine))
}
```

{% endcode %}

{% hint style="info" %}
We can get the value of a map item using it's key. However, we may be interested in knowing if the key existed or not when getting the value. We do so by using the syntax

```go
value, key_present = vending_machine["tea"]
// value: nil
// key_present: false
```

This method can be used to disambiguate between missing keys and keys with zero values like `0` or `""`.
{% endhint %}


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