Map, string slices

In Go programming we reuse common forms. We have string slices—these can contain many strings, and we can append strings as needed.

With a map, we can place string slices as the values. So we can associate string keys with lists of values. This is powerful. It helps in many Go programs.

Main example

Here we use a map of string slices in the main func. We initialize the map with two keys—each has its own string slice.

package main

import "fmt"

func main() {
    // Create map of string slices.
    m := map[string][]string {
        "cat": {"orange", "grey"},
        "dog": {"black"},
    }

    // Add a string at the dog key.
    // ... Append returns the new string slice.
    res := append(m["dog"], "brown")
    fmt.Println(res)

    // Add a key for fish.
    m["fish"] = []string{"orange", "red"}

    // Print slice at key.
    fmt.Println(m["fish"])

    // Loop over string slice at key.
    for i := range m["fish"] {
        fmt.Println(i, m["fish"][i])
    }
}
[black brown]
[orange red]
0 orange
1 red

With append, we can add elements to a string slice in a map. And with delete we can remove elements. Len will return the element count.

In Go, common things like a map that contains string slices are important to master. More complex things are nice, but often used less.