75 lines
2.2 KiB
Go
75 lines
2.2 KiB
Go
// _Slices_ are a key data type in Go, giving a more
|
|
// powerful interface to sequences than arrays.
|
|
|
|
package main
|
|
|
|
import "fmt"
|
|
|
|
func main() {
|
|
|
|
// Unlike arrays, slices are typed only by the
|
|
// elements they contain (not the number of elements).
|
|
// To create an empty slice with non-zero length, use
|
|
// the builtin `make`. Here we make a slice of `int`s
|
|
// of length `5` (initially empty-valued).
|
|
s := make([]int, 5)
|
|
fmt.Println("emp:", s)
|
|
|
|
// We can set and get just like with arrays.
|
|
s[4] = 100
|
|
fmt.Println("set:", s)
|
|
fmt.Println("get:", s[4])
|
|
|
|
// `len` returns the length of the slice as expected.
|
|
fmt.Println("len:", len(s))
|
|
|
|
// In addition to these basic operations, slices
|
|
// support several more that make them richer than
|
|
// arrays. One is the builtin `append`, which
|
|
// returns a slice containing one or more new values.
|
|
// Note that we need to accept a return value from
|
|
// append as we may get a new slice reference.
|
|
s = append(s, 6)
|
|
s = append(s, 7, 8)
|
|
fmt.Println("apd:", s)
|
|
|
|
// Slices can also be `copy`'d. Here we create an
|
|
// empty slice `c` of the same length as `s` and copy
|
|
// into `c` from `s`.
|
|
c := make([]int, len(s))
|
|
copy(c, s)
|
|
fmt.Println("cpy:", c)
|
|
|
|
// Slices support a "slice" operator, which is denoted
|
|
// with brackets containing `:`. For example, this
|
|
// gets a slice of the elements 4, 5, and 6.
|
|
l := s[4:7]
|
|
fmt.Println("sl1:", l)
|
|
|
|
// This slices up to the 7th index.
|
|
l = s[:7]
|
|
fmt.Println("sl2:", l)
|
|
|
|
// And this slices from the 4th index upwards.
|
|
l = s[4:]
|
|
fmt.Println("sl3:", l)
|
|
|
|
// We can declare and initalize a slice in a single
|
|
// line as well.
|
|
t := []int{1, 2, 3, 4, 5}
|
|
fmt.Println("dcl:", t)
|
|
|
|
// Slices can be composed into multi-dimensional data
|
|
// structures. The length of the inner slices can
|
|
// vary, unlike with multi-dimensional arrays.
|
|
twoD := make([][]int, 3)
|
|
for i := 0; i < 3; i++ {
|
|
innerLen := i + 1
|
|
twoD[i] = make([]int, innerLen)
|
|
for j := 0; j < innerLen; j++ {
|
|
twoD[i][j] = i + j
|
|
}
|
|
}
|
|
fmt.Println("2d: ", twoD)
|
|
}
|