arrays.md

📊 Arrays

• 📊 Arrays
  • 👀 Fast Lookup
  • 📋 Declaration and Initialization
  • 🔍 Accessing and Looping
  • 📄 Copying

👀 Fast Lookup

• Fixed size: Arrays have a fixed size defined at compile time
• Declaration: var arr [5]int or arr := [5]int{1,2,3,4,5}
• Size inference: Use [...] to let compiler infer size: arr := [...]int{1,2,3}
• Zero values: Uninitialized elements get zero values of their type
• Value semantics: Arrays are copied by value, not reference
• Type includes size: [3]int and [5]int are different types
• Range loop: Use for i, v := range arr to iterate

📋 Declaration and Initialization

// Without type inference
var days [7]string // ["", "", "", "", "", "", ""]

// With type inference
numArray1 := [5]int{1, 2, 3, 4, 5}

// With `...` to let the compiler infer the size
numArray2 := [...]{1, 2, 3} // compiler infers the size to be 3 and type to be int

🔍 Accessing and Looping

days := [...]{"Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"}

// Accessing
days[0] // "Monday"
days[6] // "Sunday"

// Looping using len()
for i := 0; i < len(days); i++ {
    fmt.Println(days[i])
}

// Looping with range
for i, day := range days {
    fmt.Println(i, day)
}

📄 Copying

When an array is copied, a new array is created and the values are copied from the original array to the new array.

arr1 := [3]int{1, 2, 3}
arr2 := arr1 // arr2 is a copy of arr1
arr2[0] = 100
fmt.Println(arr1) // [1, 2, 3]
fmt.Println(arr2) // [100, 2, 3]

var arr3 [3]float64
arr3 = arr1 // Error: cannot assign [3]int to [3]float64. Type must match.