Class 29 - Go Arrays and Memory Layout

📅 Date: April 24, 2025

🔑 Key Concepts

✅ What is an Array?

• An array is a fixed-size collection of elements of the same type.
• In Go, arrays are value types, meaning they are copied when passed around.

🧠 Array in Go

var arr [2]int       // Declares an array of 2 integers. Default values: [0, 0]
arr[0] = 3           // Assigning values using index
arr[1] = 6

// Short way of declaring an array with values
arr := [2]int{3, 6}

💡 Indexing

• Arrays in Go are zero-indexed, meaning the first element is accessed with array[0].

⚙️ Default Values

• If you declare an array without initializing it, Go assigns default values:
  • For int, float, etc: 0
  • For string: "" (empty string)
  • For bool: false
  • For pointers/interfaces: nil

🔍 Memory Layout Visualization

Example:

arr := [2]int{3, 6}

Memory Layout

Note: The actual address is abstract. The concept is: array elements are stored contiguously in memory.

Another example:

arr2 := [3]string{"I", "love", "you"}

Accessing arr2[1] returns "love".

🧪 Full Code Example (From Class)

package main

import "fmt"

var arr2 = [3]string{"I", "love", "you"}

func main() {
    arr := [2]int{3,6}
    fmt.Println(arr)
    fmt.Println(arr2)
    fmt.Println(arr2[1])
}

📦 Summary

• Arrays are great for working with fixed-size collections.
• Be aware of default values.
• They're stored contiguously in memory.
• Go makes it easy to work with arrays, and it's a good base before moving to slices!