Slices are created with the make function. It works by allocating a zeroed array and returning a slice that refers to that array:

a := make([]int, 5)  // len(a)=5

To specify a capacity, pass a third argument to make:

b := make([]int, 0, 5) // len(b)=0, cap(b)=5b = b[:cap(b)] // len(b)=5, cap(b)=5b = b[1:]      // len(b)=4, cap(b)=4

package main import "fmt"func main() {    a := make([]int, 5)    printSlice("a", a)    b := make([]int, 0, 5)    printSlice("b", b)    c := b[:2]    printSlice("c", c)    d := c[2:5]    printSlice("d", d)}func printSlice(s string, x []int) {    fmt.Printf("%s len=%d cap=%d %v\n",        s, len(x), cap(x), x)}

A Tour of Go Making slices