Go slices length and capacity
A slice has both a length and a capacity.
The length of a slice is the number of elements it contains.
The capacity of a slice is the number of elements in the underlying array, counting from the first element in the slice.
The length and capacity of a slice s can be obtained using the expressions len(s) and cap(s)
You can extend a slice’s length by re-slicing it, provided it has sufficient capacity. If you try to extend it beyond its capacity, it will panic
1package main
2
3import "fmt"
4
5func main() {
6 s := []int{2, 3, 5, 7, 11, 13}
7 printSlice(s)
8
9 // Slice the slice to give it zero length.
10 s = s[:0]
11 printSlice(s)
12
13 // Extend its length.
14 s = s[:4]
15 printSlice(s)
16
17 // Drop its first two values.
18 s = s[2:]
19 printSlice(s)
20
21 s = s[:]
22 printSlice(s)
23}
24
25func printSlice(s []int) {
26 fmt.Printf("len=%d cap=%d %v\n", len(s), cap(s), s)
27}
28
29// Output:
30// len=6 cap=6 [2 3 5 7 11 13]
31// len=0 cap=6 []
32// len=4 cap=6 [2 3 5 7]
33// len=2 cap=4 [5 7]
34// len=2 cap=4 [5 7]
References
Next -> slice-zero-value
Next -> creating-a-slice-with-make
#slice #structured #capacity #length #array #data #golang #type