How to modify the value of a slice in golang

Modification method: 1. Use the append() function to add new values, the syntax "append(slice, value list)"; 2. Use the append() function to delete elements, the syntax "append(a[:i]" , a[i N:]...)"; 3. Reassign the value directly according to the index, the syntax is "slice name [index] = new value".

The operating environment of this tutorial: Windows 7 system, GO version 1.18, Dell G3 computer.

Add, delete, modify and query slices in Go language

• A slice is a dynamic array and you can use the append() function to add elements
• There is no special method to delete slice elements in the go language. We can use the characteristics of the slice itself to delete elements.
• Since the slice is a reference type, the original content will be modified through assignment. Go provides the copy() function to copy the slice

1. Add elements

package main
import "fmt"
func main() {
 a := []int{}
 a = append(a, 1)
 a = append(a, 2)
 a = append(a, 3, 4, 5) //添加多个元素
 fmt.Printf("a: %v\n", a)
 fmt.Println("---------------------")
 a1 := []int{3, 4, 5}
 a2 := []int{1, 2}
 a2 = append(a2, a1...) //添加另外一个切片进去
 fmt.Printf("a2: %v\n", a2)
}
//输出结果如下
a: [1 2 3 4 5]
---------------------
a2: [1 2 3 4 5]

2. Delete element

package main
import "fmt"
func main() {
 var s1 = []int{1, 2, 3, 4}
 fmt.Println("---删除之前---")
 fmt.Printf("s1: %v\n", s1)
 //删除3这个元素，它的下标索引为2
 s1 = append(s1[:2], s1[3:]...)
 fmt.Println("---删除之后---")
 fmt.Printf("s1: %v\n", s1)
}
//执行结果如下
---删除之前---
s1: [1 2 3 4]
---删除之后---
s1: [1 2 4]

Formula for deleting elements:

To delete the element with index index from slice a, the operation method is as follows

a = append(a[:index], a[index+1:]...)

3. Modify the slice element

package main
import "fmt"
func main() {
 var s1 = []int{1, 2, 3, 4, 5}
 s1[1] = 100 //索引1的值改为100
 fmt.Printf("s1: %v\n", s1)
}
//输出结果如下
s1: [1 100 3 4 5]

4. Find the slice element

package main
import "fmt"
func main() {
 var s1 = []int{1, 2, 3, 4, 5}
 var key = 2 //查找2所在的位置
 for i, v := range s1 {
  if v == key {
   fmt.Printf("s1: %v\n", s1)
   fmt.Printf("索引为: %v\n", i)
  }
 }
}
//输出结果如下
s1: [1 2 3 4 5]
索引为: 1

##5. Copy the slice

package main
import "fmt"
func main() {
 var s1 = []int{1, 2, 3, 4, 5}
 var s2 = s1
 s2[0] = 100
 fmt.Printf("s1: %v\n", s1)
 fmt.Printf("s2: %v\n", s2)
}
//输出结果如下
s1: [100 2 3 4 5]
s2: [100 2 3 4 5]

Use Modifications by the copy method will not affect the value of the source slice

package main
import "fmt"
func main() {
 var s1 = []int{1, 2, 3, 4, 5}
 var s2 = make([]int, 4)  //需要make一个切片的类型，指定有5个元素
 copy(s2, s1) //指定复制的切片
 s2[0] = 100
 fmt.Printf("s1: %v\n", s1)
 fmt.Printf("s2: %v\n", s2)
}
//输出结果
s1: [1 2 3 4 5]
s2: [100 2 3 4 5]