Go Maps

What are Maps?

Quite simply, maps map a key to a value. You can also think of maps as an unordered list of key-value pairs, with unique keys. Keys must have the same data type and values must have the same data types. However, keys and values don't need to have the same data type.

Creating a Map

Below is the general form of a map:

map1 := map[KeyType]ValueType{key1:value1, key2:value2,...}
    

Replace KeyType with the data type of the keys and ValueType with the data type of the values. Then, inside the curly brackets, you can put key:value pairs, seperated by commas.

For example:

website := map[string]string{"name":"Learnmonkey", "founded":"2022", domain:"learnmonkey.github.io"}
    

Accessing Map Elements

To access a map element, we type map[key]. For example:

website := map[string]string{"name":"Learnmonkey", "founded":"2022", domain:"learnmonkey.github.io"}
fmt.Println(website["name"])
fmt.Println(website["founded"])
fmt.Println(website["domain"])
    

The above code outputs:

Learnmonkey
2022
learnmonkey.github.io
    

Updating and Adding Map Elements

To add and update map elements, we simply type map[key] = value.

Removing Map Elements

To remove map elements, we use the delete function: delete(map, key)

Checking if a Map Element Exists

To check if a map element exists, we type:

In the above code, x represents the value of the value of the corresponding key (which will be empty if that key doesn't exist in the map) and y is a boolean which is true if the key is in the map and is false if the key isn't in the map.

If we just want to check if a map element exists and not know the value, we can type:

That way, the value won't be assigned to any variable.