Golang基础常识性面试中常见的六大陷阱及应对技巧总结

package main
import "fmt"
func main() {
  var nilSlice []string  // 创建一个 nil 切片
  emptySlice0 := make([]int, 0)  // 方法1：创建一个空切片（零切片）
  var emptySlice1 = []string{}   // 方法2：创建一个空切片
  fmt.Printf("\nnilSlice---> Nil:%v Len:%d Capacity:%d", nilSlice == nil, len(nilSlice), cap(nilSlice))
  fmt.Printf("\nemptySlice0---> nil:%v Len:%d Capacity:%d", emptySlice0 == nil, len(emptySlice0), cap(emptySlice0))
  fmt.Printf("\nemptySlice1---> nil:%v Len:%d Capacity:%d", emptySlice1 == nil, len(emptySlice1), cap(emptySlice1))
  // nil切片和空切片都可以正常 append数据
  nilSlice = append(nilSlice, "sss")
}
/*
Nil:true Len:0 Capacity:0
nil:false Len:0 Capacity:0
nil:false Len:0 Capacity:0[sss]
 */

package main

import (
   "fmt"
   "reflect"
   "unsafe"
)

func main() {
   a :="aaa"
   ssh := *(*reflect.StringHeader)(unsafe.Pointer(&a))
   b := *(*[]byte)(unsafe.Pointer(&ssh))
   fmt.Printf("%v---%T",b,b)  // [97 97 97]---[]uint8
}

type SliceHeader struct {
  Data uintptr
  Len  int
  Cap  int
}

package main

func main() {
  var m1 map[string]string    // 创建一个 nil map
  println("m1为nil: ", m1==nil)
  // 报错 => panic: assignment to entry in nil map
  //m1["name"] = "tom"

  var m2 =  make(map[string]string)  // 创建一个空map
  m2["name"] = "jack"                // 空map可以正常
  println("m2为nil: ", m2==nil)
}

package main
import "fmt"
func main() {
  s := []int{1,2,3,4,5}
  for _, v:=range s {
    s =append(s, v)
    fmt.Printf("len(s)=%v\n",len(s))
  }
}
/*
len(s)=6
len(s)=7
len(s)=8
len(s)=9
len(s)=10
 */

package main
import "fmt"
func main() {
  var nums = []int{1, 2, 3, 4, 5}
  var res []*int
  for _, num := range nums {
    res = append(res, &num)
    //fmt.Println("num:", num)
  }
  for _, r := range res {
    fmt.Println("res:", *r)
  }
}
/*
res: 5
res: 5
res: 5
res: 5
res: 5
 */

package main
import "fmt"
func main() {
  var nums = []int{1, 2, 3, 4, 5}
  var res []*int
  for i := 0; i < len(nums); i++ {
    res = append(res, &nums[i])
  }
  fmt.Println("res:", res)
  for _, r := range res {
    fmt.Println("res:", *r)
  }
}

package main
import "fmt"
func main() {
  var nums = []int{1, 2, 3, 4, 5}
  var res []*int
  for _, num := range nums {
    numTemp := num // 创建一个新的临时变量
    res = append(res, &numTemp)
  }
  for _, r := range res {
    fmt.Println("res:", *r)
  }
}
/*
res: 1
res: 2
res: 3
res: 4
res: 5
 */