package main
import (
  "fmt"
  "strconv"
)
//bin表示转化后的位数
func convertToBin(n int,bin int) string{
  var b string
  switch {
  case n==0:
    for i:=0;i<bin;i++{
      b+="0"
    }
  case n>0:
    //strcov.Itoa 将 1 转为 "1" , string(1)直接转为assic码
    for ; n>0;n/=2{
      b=strconv.Itoa(n%2)+b
    }
    //加0
    j:=bin-len(b)
    for i:=0;i<j;i++{
      b="0"+b
    }
  case n<0:
    n=n*-1
    // fmt.Println("变为整数：",n)
    s:=convertToBin(n,bin)
    // fmt.Println("bin:",s)
    //取反
    for i:=0;i<len(s);i++{
      if s[i:i+1]=="1"{
        b+="0"
      }else{
        b+="1"
      }
    }
    // fmt.Println("~bin :",b)
    //转化为整形，之后加1 这里必须要64，否则在转化过程中可能会超出范围
    n,err :=strconv.ParseInt(b,2,64)
    if err!=nil{
      fmt.Println(err)
    }
    //转为bin
    //+1
    b=convertToBin(int(n+1),bin)
  }
  return b
}
func main(){
  fmt.Println(
    convertToBin(5,8), //101
    convertToBin(13,8), //1101
    convertToBin(11111,8),
    convertToBin(0,8),
    convertToBin(1,8),
    convertToBin(-5,8),
    convertToBin(-11111,8),
  )
}

变为整数： 11111
bin: 10101101100111
~bin : 01010010011000
结果：1010010011001

变为整数： 1
bin: 00000001
~bin : 11111110
结果：11111111