How to declare a slice in Go?

In Go, slices can be declared in several ways:

1. Using a slice literal:

   // Declare and initialize a slice of integers
   s := []int{1, 2, 3}
   

2. Using make:

   // Declare a slice of integers with length 5 and capacity 5
   s1 := make([]int, 5)
   // Declare a slice of integers with length 0 and capacity 10
   s2 := make([]int, 0, 10)
   

   Syntax make([]Type, length, capacity):

   • Type: The element type of the slice.
   • length: The initial length of the slice (number of accessible elements).
   • capacity (optional): The capacity of the slice (maximum number of elements that can be added before reallocating the underlying array). If not specified, it defaults to length.

3. Declaring a slice without initialization (default value nil):

   // Declare a slice of integers with default value nil
   var s []int
   

   A nil slice has length 0, capacity 0, and no underlying array.

4. Creating a slice from an existing array or another slice:

   arr := [5]int{10, 20, 30, 40, 50}
   // Create a slice from the first three elements of the array
   s := arr[0:3] // [10, 20, 30]
   
   otherSlice := []string{"a", "b", "c", "d", "e"}
   // Create a new slice from a subset of another slice
   subSlice := otherSlice[1:4] // ["b", "c", "d"]
   

   Syntax arrayOrSlice[low:high] or arrayOrSlice[low:high:max]:

   • low: Starting index (inclusive).
   • high: Ending index (exclusive).
   • max (optional): Index that determines the capacity of the new slice.

Each of these methods has its own features and is used depending on the use case.