Creating a slice with make

Slices can be created with the built-in make function; this is how you create dynamically-sized arrays.

The make function allocates a zeroed array and returns 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)=5
 
b = b[:cap(b)] // len(b)=5, cap(b)=5
b = b[1:]      // len(b)=4, cap(b)=4

making-slices.go

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)
}