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Creating Maps in GoLang: Step-by-Step Tutorial

A Map is a type of data structure, it is a collection of unorder pairs of key-value. With the help of map we can easily do retrieve, update and insert operations.

Syntax:

var mymap map[keytype]valuetype 

Use Case 1:

package main

import “fmt”

func main() {

            var mymap map[int]int

            if mymap == nil {

                        fmt.Println(“true”)

            } else {

                        fmt.Println(“False”)

            }

}

Output:

Use Case 2:

package main

import “fmt”

func main() {

            var mymap map[int]int

            if mymap == nil {

                        fmt.Println(“true”)

            } else {

                        fmt.Println(“False”)

            }

            map2 := map[int]string{

                        10: “Prwatech”,11: “Bangalore”,

            }

            fmt.Println(“Map 2 value”, map2)

}

Output:

Use Case 3: Create a map using make() function.

package main

import “fmt”

func main() {

            // Creating a map

            // Using make() function

            var map1 = make(map[int]string)

            fmt.Println(map1)

            // As we already know that make() function

            / always returns a map which is initialized

            // So, we can add values in it

            map1[1] = “Prwatech”

            map1[2] = “Bangalore”

            fmt.Println(map1)

}

Output:

Use Case 4: Adding new key elements and update operation:

package main

import “fmt”

// Main function

func main() {

            // Creating and initializing a map

            m_a_p := map[int]string{

                        90: “Prwatech”,

                        91: “Bangalore”,

                        92: “Big Data”,

            }

            fmt.Println(“Original map: “, m_a_p)

            // Adding new key-value pairs in the map

            m_a_p[93] = “Python”

            m_a_p[94] = “Golang”

            fmt.Println(“Map after adding new key-value pair:\n”, m_a_p)

            // Updating values of the map

            m_a_p[93] = “Gcp”

            fmt.Println(“\nMap after updating values of the map:\n”, m_a_p)

}

Output:

Use Case 5:Retrieving values with the help of keys:

package main

import “fmt”

// Main function

func main() {

            // Creating and initializing a map

            m_a_p := map[int]string{

                        90: “Red”,

                        91: “Yellow”,

                        92: “Orange”,

                        93: “Blue”,

                        94: “White”,

            }

            fmt.Println(“Original map: “, m_a_p)

            // Retrieving values with the help of keys

            value_1 := m_a_p[90]

            value_2 := m_a_p[93]

            fmt.Println(“Value of key[90]: “, value_1)

            fmt.Println(“Value of key[93]: “, value_2)

}

Output:

Use Case 6:Deleting keys

package main

import “fmt”

// Main function

func main() {

            // Creating and initializing a map

            m_a_p := map[int]string{

                        90: “Red”,

                        91: “Yellow”,

                        92: “Orange”,

                        93: “Blue”,

                        94: “White”,

            }

            fmt.Println(“Original map: “, m_a_p)

            // Deleting keys

            // Using delete function

            delete(m_a_p, 90)

            delete(m_a_p, 93)

            fmt.Println(“Map after deletion: “, m_a_p)

}

Output: