Why not always use arrays instead of slices?

Arrays in Go have a fixed size, which is specified at declaration, and this size is part of the type. This means that arrays are not flexible and cannot change their length dynamically.

Slices are a more convenient and flexible type that represents a dynamic view of an array. They contain a pointer to an array, a length, and a capacity, which allows resizing the slice, adding elements (via append), and passing slices as more versatile structures.

Why not always use arrays:

• Arrays are fixed in size, which is inconvenient for dynamic data.
• Passing an array to a function copies the entire array, which is costly in terms of memory and time.
• Slices are passed by reference to the array, which is more efficient.

Example:

var arr [3]int = [3]int{1, 2, 3} // fixed size
var s []int = arr[:2]            // slice of part of the array
s = append(s, 4)                 // slice can be extended (if capacity allows)

Thus, slices are a more versatile and convenient tool for working with sequences of data in Go.