Comments (9)
from go-patterns.
请看这里
func main() {
s := []int{0, 1, 2, 3, 4, 5, 6, 7}
//删除第2个元素,从0开始算
s = append(s[:2], s[2+1:]...)
printInfo(s)
//结果:
//[0 1 3 4 5 6 7]
//len: 7 cap: 8
}
func printInfo(s []int) {
fmt.Println(s)
fmt.Println("len:", len(s), "cap:",cap(s))
}
from go-patterns.
请看这里
func main() {
s := []int{0, 1, 2, 3, 4, 5, 6, 7}
//删除第2个元素,从0开始算
s = append(s[:2], s[2+1:]...)
printInfo(s)
//结果:
//[0 1 3 4 5 6 7]
//len: 7 cap: 8
}func printInfo(s []int) {
fmt.Println(s)
fmt.Println("len:", len(s), "cap:",cap(s))
}
前后s的地址是不同的,通过append操作后,实际上新开辟一块地址空间在s[:2]上进行扩容,原来部分会被go的垃圾回收处理, 参考以下代码
i := []int{1,2,3}
fmt.Printf("append前地址%p\n", i)
i = append(i, 4)
fmt.Printf("append前地址%p\n", i)
from go-patterns.
你这个代码是增加元素,不是删除,超出容量当然要重新开辟一个空间
from go-patterns.
你看这里:
func main() {
s := []int{0, 1, 2, 3, 4, 5, 6, 7}
fmt.Printf("%p\n", s)
//删除第2个元素,从0开始算
s = append(s[:2], s[2+1:]...)
fmt.Printf("%p\n", s)
fmt.Println(s)
fmt.Println("len:", len(s), "cap:",cap(s))
//结果:
//0xc0000a6000
//0xc0000a6000
//[0 1 3 4 5 6 7]
//len: 7 cap: 8
}
from go-patterns.
你看这里:
func main() {
s := []int{0, 1, 2, 3, 4, 5, 6, 7}
fmt.Printf("%p\n", s)
//删除第2个元素,从0开始算
s = append(s[:2], s[2+1:]...)
fmt.Printf("%p\n", s)
fmt.Println(s)
fmt.Println("len:", len(s), "cap:",cap(s))
//结果:
//0xc0000a6000
//0xc0000a6000
//[0 1 3 4 5 6 7]
//len: 7 cap: 8
}
append我理解错误了,是只有超过cap的时候底层数组重现分配内存。
重现创建一个slice放剩下元素的代码能粘贴一下吗,在做少量删除的时候直接append时内存的计算时间耗时会少些
from go-patterns.
https://github.com/golang/go/wiki/SliceTricks
from go-patterns.
s := []string{"a", "b"}
d := "b"
var s2 []string
for _,v := range s {
if v != d {
s2 = append(s2, v)
}
}
from go-patterns.
s := []string{"a", "b"}
d := "b"
var s2 []string
for _,v := range s {
if v != d {
s2 = append(s2, v)
}
}
空间换时间吧, 少量删除结果还是直接在原来基础上更快些
func main() {
s := []string{"a", "b", "c", "d"}
begin := time.Now()
s = append(s[:1], s[2:]...)
end := time.Now()
fmt.Println(end.UnixNano() - begin.UnixNano()) //0
m := []string{"a", "b", "c", "d"}
begin = time.Now()
var s2 []string
for _, v := range m {
if v != "b" {
s2 = append(s2, v)
}
}
end = time.Now()
fmt.Println(end.UnixNano() - begin.UnixNano()) //1000~ 7000
}
from go-patterns.
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from go-patterns.