Collections in Go

In Go, collections allow us to store 0, 1, or many of another type. There are three main types of collection:

Array

var numbers [5]int
numbers[0] = 10
numbers[1] = 20

// Or initialize with values
scores := [3]int{95, 87, 92}

You can think of arrays as a fixed-size list of items. Once you declare an array with a specific size (like [5]int), that size cannot change. Arrays are useful when you know exactly how many elements you need and that number won't change during your program's execution.

// Accessing array elements
fmt.Println(scores[0]) // Prints: 95
fmt.Println(scores[2]) // Prints: 92

Slice

var names []string
names = append(names, "Alice")
names = append(names, "Bob")

// Or initialize with values
fruits := []string{"apple", "banana", "orange"}

// You can also create a slice from an array
slice := scores[0:2] // Takes first 2 elements from scores array

Slices are similar to arrays but with one key difference: they have a dynamic size. You can add or remove elements as needed using functions like append(). Slices are the most commonly used collection type in Go because of their flexibility.

// Growing a slice dynamically
fruits = append(fruits, "mango", "strawberry")
fmt.Println(len(fruits)) // Prints: 5

Map

// Create a map with string keys and int values
ages := make(map[string]int)
ages["Alice"] = 30
ages["Bob"] = 25

// Or initialize with values
capitals := map[string]string{
    "USA": "Washington D.C.",
    "Japan": "Tokyo",
    "France": "Paris",
}

// Access a value
fmt.Println(ages["Alice"]) // Prints: 30

Maps are key-value pairs, similar to dictionaries in Python or objects in JavaScript. They allow you to store data where each value is associated with a unique key. Maps are great when you need to look up values quickly by a specific identifier.

// Looking up values in a map
capital := capitals["Japan"]
fmt.Println(capital) // Prints: Tokyo

// Check if a key exists
capital, exists := capitals["Germany"]
if exists {
    fmt.Println(capital)
} else {
    fmt.Println("Capital not found")
}

Assignment

For this challenge, create two different collection types:

1. Slice: Create a slice of strings called names which should contain 3 names: "Goku", "Vegeta", and "Gohan" in that exact order

2. Map: Create a map called powerLevels that maps character names (strings) to their power levels (unsigned integers). Include the following entries:

   • "Goku": 9001
   • "Vegeta": 8500
   • "Gohan": 8000

Once created, print out:

• The second name from the names slice
• Goku's power level from the powerLevels map