Day 8: Mastering Maps in Go: Key-Value Collections

Day 8: Mastering Maps in Go - Key-Value Collections

Maps are Go’s built-in associative data structure for storing key-value pairs. Today, we’ll explore how to declare, initialize, and manipulate maps in Go.

Step 1: Declaring and Initializing Maps

Maps in Go are declared using the make() function or by using map literals:

m := make(map[string]int)
m["apple"] = 5
m["banana"] = 10

fmt.Println(m)

Alternatively, you can initialize maps using literals:

m := map[string]int{"apple": 5, "banana": 10}

Step 2: Accessing and Modifying Map Values

You can access map values using the key:

value := m["apple"]
fmt.Println(value)  // Output: 5

To check if a key exists in a map, use the following pattern:

value, exists := m["orange"]
if exists {
    fmt.Println("Key exists:", value)
} else {
    fmt.Println("Key does not exist")
}

Step 3: Deleting Map Entries

To remove a key-value pair from a map, use the delete() function:

delete(m, "banana")
fmt.Println(m)

Practical Exercise

Write a Go program that creates a map of fruits and their quantities, modifies an entry, deletes another, and prints the final map:

package main

import "fmt"

func main() {
    fruits := map[string]int{
        "apple":  5,
        "banana": 10,
        "orange": 8,
    }

    // Modify the quantity of apples
    fruits["apple"] = 7

    // Delete oranges from the map
    delete(fruits, "orange")

    fmt.Println(fruits)
}