How Can I Allocate Arrays with Variable Size in Go?

Allocating Arrays with Variable Size in Go

Unlike constant-sized arrays declared using const, Go does not allow the direct allocation of arrays with runtime-determined sizes. This is evident in the following illegal code:

n := 1
var a [n]int

However, there is a solution: utilize slices instead of arrays. Slices are references to underlying arrays and provide dynamic resizing capabilities. The built-in make() function is used to create slices and their underlying arrays. It takes three arguments:

• Length: Specifies the initial length of the slice
• Capacity: Indicates the maximum capacity of the underlying array
• Element Type: Defines the type of elements in the slice

By creating a slice using make(), we indirectly allocate an array with a runtime size:

n := 12
s := make([]int, n, 2*n)

In this case, an array of size 2*n is allocated, and s refers to a slice containing the first n elements of the array.

It remains unclear why Go does not allow direct allocation of variable-sized arrays, but the solution of using slices provides a flexible and efficient alternative. As a result, it is recommended to use slices in most scenarios when working with dynamic data structures in Go.

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