Appending new elements to a slice is a common operation, for which Go provides a built-in append function.
func append(slice []T, elems ...T) []T
If the slice capacity is sufficient, the target will be sliced again to accommodate the new element.
If the slice capacity is not enough, a new array will be allocated. append returns an updated slice. Therefore, it is necessary to store the result of append in a variable that holds the slice itself.
The following is a complete code example.
package main
import "fmt"
func main() {
s := make([]int, 3, 4)
printSlice(s)
// 切片容量足够
s = append(s, 1)
printSlice(s)
// 切片容量不够
s = append(s, 1)
printSlice(s)
// 可以一次性添加多个元素
s = append(s, 2, 3, 4)
printSlice(s)
}
func printSlice(s []int) {
fmt.Printf("len=%d cap=%d %v\n", len(s), cap(s), s)
}Below is the program output:
len=3 cap=4 [0 0 0]
len=4 cap=4 [0 0 0 1]
len=5 cap=8 [0 0 0 1 1]
len=8 cap=8 [0 0 0 1 1 2 3 4]