How can I convert an int64 into a byte array in go?

Question

I have an id that is represented at an int64. How can I convert this to a []byte? I see that the binary package does this for uints, but I want to make sure I don't break negative numbers.

Answer 1

Converting between int64 and uint64 doesn't change the sign bit, only the way it's interpreted.

You can use Uint64 and PutUint64 with the correct ByteOrder

http://play.golang.org/p/wN3ZlB40wH

i := int64(-123456789)  fmt.Println(i)  b := make([]byte, 8) binary.LittleEndian.PutUint64(b, uint64(i))  fmt.Println(b)  i = int64(binary.LittleEndian.Uint64(b)) fmt.Println(i) 

output:

-123456789 [235 50 164 248 255 255 255 255] -123456789 

Answer 2

You can use this too:

var num int64 = -123456789  b := []byte(strconv.FormatInt(num, 10))  fmt.Printf("num is: %v, in string is: %s", b, string(b)) 

Output:

num is: [45 49 50 51 52 53 54 55 56 57], in string is: -123456789