为什么如果我打印bs,在调用Read()之前,它什么都不打印,但在调用file.Read(bs)之后,它显示了test.txt文件的内部。除非bs只是参数,Read()如何改变它?packagemainimport("os""fmt")funcmain(){file,err:=os.Open("test.txt")iferr==nil{}else{}stat,_:=file.Stat()bs:=make([]byte,stat.Size())fmt.Println(string(bs))bsf,err:=file.Read(bs)iferr!=nil{fmt.Println(err)f