package main

import (
	"fmt"
	"maps"
)

func main() {

	// A map maps keys to values. The zero value of a map is nil. A nil map has no keys, nor can keys be added.
	var m map[string]int

	// To create a map, use the builtin make function. The make function allocates and
	// initializes a hash map data structure and returns a map value that points to it.
	m = make(map[string]int)

	// Set key/value pairs using typical name[key] = val syntax.
	m["k1"] = 7
	m["k2"] = 13

	fmt.Println("map:", m)

	// Get a value for a key with name[key].
	v1 := m["k1"]
	fmt.Println("v1:", v1)

	// If the key is not present in the map, the result is the zero value for the map's value type.
	v3 := m["k3"]
	fmt.Println("v3:", v3)

	fmt.Println("len:", len(m))

	// The builtin delete removes key/value pairs from a map.
	delete(m, "k2")
	delete(m, "k2") // Deleting a non-existent key does not cause an error.
	fmt.Println("map:", m)

	// The builtin "maps" package provides a function Clear to remove all key/value pairs from a map.
	clear(m)
	fmt.Println("map:", m)

	// The optional second return value when getting a value from a map indicates if the key was present in the map.
	_, prs := m["k2"]
	fmt.Println("prs:", prs)

	// Map literals are like struct literals, but the keys are required.
	n := map[string]int{"foo": 1, "bar": 2}
	fmt.Println("map:", n)

	// The builtin "maps" package provides a function Equal to compare two maps for equality.
	n2 := map[string]int{"foo": 1, "bar": 2}
	if maps.Equal(n, n2) {
		fmt.Println("n == n2")
	}
}