What is map in golang
A map is a builtin type in Go that is used to store key-value pairs, where each key is unique. all the individual keys needs to be a particular type and all the individual values of another type although the keys and values can be of different types.
Declaring map variables
following are ways to declare maps
//{declares empty map; key is of type int and value of type string}
1. var themap map[int]string//{declares and initialises empty map using the make function}
2. themap := make(map[int]string)//{one can declare and initialise at same time; pay attention to the comma after "green"}
3. colors := map[int]string{ 1: "Voilet", 2: "Indigo", 3: "Blue",}
Appending and deleting values in a map
The syntax for adding new items to a map is the same as that of arrays, if you try to add to maps which have not been initialised it will result in “panic: assignment to entry in nil map”
colors[4] = "Green"colors[5] = "Yellow"and to delete, the below will delete the value with key 4 namely "Green"delete(colors,4)
Looping through a map
lets create a function(printMap) below to loop through the values of a map which gets passed as reference. the below function also showcases the use of len which gets us the length/size of the map.
func printMap(c map[int]string) { fmt.Println("length of map is ", len(c)) for i, colorname := range c { fmt.Println("item @", i, " colour name is ", colorname) }}
Getting individual values of keys
Before retrieving a single value we want to check if that key-value exists in the map, below code show how to check and retrieve at the same time
colorFive, ok := colors[5]if ok == true { fmt.Println(colorFive)}
