How to Create Nested Maps in Go

1. Introduction

Nested maps in Go, sometimes referred to as maps of maps, are a powerful way to manage complex hierarchical data structures. This construct is particularly useful for scenarios where you need to associate keys with values that are themselves maps. This post will explain how to implement nested maps in Go.

2. Program Steps

1. Declare a nested map.

2. Initialize the nested map with values.

3. Access and modify data within the nested map.

4. Iterate over a nested map to print its contents.

3. Code Program

A nested map is a map wherein the value type is another map. This allows for the creation of multi-dimensional data structures with keys at various levels. It’s a useful way to represent and work with data in a hierarchical or tabular format.

Here is the complete Go program to demonstrate how to create nested Maps:
package main

import "fmt"

func main() {
	// Step 1: Declare a nested map
	var networkMap map[string]map[string]bool

	// Step 2: Initialize the nested map with values
	networkMap = make(map[string]map[string]bool)
	networkMap["server1"] = make(map[string]bool)
	networkMap["server1"]["192.168.1.10"] = true
	networkMap["server1"]["192.168.1.11"] = false
	networkMap["server2"] = make(map[string]bool)
	networkMap["server2"]["10.0.0.5"] = true

	// Step 3: Modify data in the nested map
	networkMap["server1"]["192.168.1.11"] = true // Update IP status

	// Step 4: Iterate over the nested map
	fmt.Println("Network Map Status:")
	for server, ips := range networkMap {
		for ip, status := range ips {
			fmt.Printf("Server: %s, IP: %s, Status: %t\n", server, ip, status)
		}
	}
}

Output:

Network Map Status:
Server: server1, IP: 192.168.1.10, Status: true
Server: server1, IP: 192.168.1.11, Status: true
Server: server2, IP: 10.0.0.5, Status: true

Explanation:

1. package main - Defines the package for the Go program.

2. import "fmt" - Imports the Format package used for printing formatted output.

3. networkMap - A nested map with string keys at the first level and a map of string keys to boolean values at the second level is declared.

4. networkMap is initialized, defining two sub-maps corresponding to "server1" and "server2".

5. The sub-maps are populated with IP addresses and their respective statuses.

6. An IP status is updated in the nested map to illustrate how you can change the values within.

7. A nested for loop iterates over networkMap and its sub-maps, printing the server names, IP addresses, and their statuses.

8. The output displays the status of IP addresses for each server in the network map.


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