golang 判断元素是否在slice或数组里

package main 
import "fmt" 
import "github.com/wxnacy/wgo/arrays" 
//go get github.com/wxnacy/wgo/arrays   安装包 

func main() {
 str := "342"
 var numbers []string
 numbers = append(numbers, "3332", "342", "ssddd", "ssss", "%%%%") 
 index := arrays.ContainsString(numbers, str)
 if index == -1 {
  fmt.Printf("not exists") //-1说明不存在
 } else {
  fmt.Println(index) //存在则会返回元素的下标 
 }
}