如何在go中将int64转换为字节数组？

问题描述：

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.

我有一个用int64 code>表示的ID。如何将其转换为 [] byte code>？我看到二进制包为uint做到了这一点，但我想确保我不会破坏负数。 p> div>

答

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

答

The code:

var num int64 = -123456789

// convert int64 to []byte
buf := make([]byte, binary.MaxVarintLen64)
n := binary.PutVarint(buf, num)
b := buf[:n]

// convert []byte to int64
x, n := binary.Varint(b)
fmt.Printf("x is: %v, n is: %v
", x, n)

outputs

x is: -123456789, n is: 4

答

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

答

If you don't care about the sign or endianness (for example, reasons like hashing keys for maps etc), you can simply shift bits, then AND them with 0b11111111 (0xFF):

(assume v is an int32)

b := [4]byte{
        byte(0xff & v),
        byte(0xff & (v >> 8)),
        byte(0xff & (v >> 16)),
        byte(0xff & (v >> 24))}

(for int64/uint64, you'd need to have a byte slice of length 8)

如何在go中将int64转换为字节数组？

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