How to convert type to byte array golang

How to Convert Type of one kind to byte array

Here is the working example

package main

import (
	"bytes"
	"fmt"
	"reflect"
)

type Signature [5]byte

const (
	/// Number of bytes in a signature.
	SignatureLength = 5
)

func main() {

	var bytes0to64 Signature = SignatureFromBytes([]byte("Here is a string.........."))
	fmt.Println(reflect.TypeOf(bytes0to64))

	res := bytes.Compare([]byte("Test"), bytes0to64)
	if res == 0 {
		fmt.Println("!..Slices are equal..!")
	} else {
		fmt.Println("!..Slice are not equal..!")
	}

}

func SignatureFromBytes(in []byte) (out Signature) {
	byteCount := len(in)
	if byteCount == 0 {
		return
	}

	max := SignatureLength
	if byteCount < max {
		max = byteCount
	}

	copy(out[:], in[0:max])
	return
}

In Go lang defined

type Signature [5]byte

So this is expected

var bytes0to64 Signature = SignatureFromBytes([]byte("Here is a string.........."))
	fmt.Println(reflect.TypeOf(bytes0to64))

It just output the Type to

main.Signature

This is correct, now I want to get the byte array from this for the next level of processing and get a compilation error

./prog.go:23:29: cannot use bytes0to64 (type Signature) as type []byte in argument to bytes.Compare

Go build failed.

The error is right only there is a mismatch on comparison. Now how should i convert the Signature type to byte array

Since Signature is a byte array, you may simply slice it:

bytes0to64[:]

This will result in a value of []byte.

Testing it:

res := bytes.Compare([]byte("Test"), bytes0to64[:])
if res == 0 {
	fmt.Println("!..Slices are equal..!")
} else {
	fmt.Println("!..Slice are not equal..!")
}
res = bytes.Compare([]byte{72, 101, 114, 101, 32}, bytes0to64[:])
if res == 0 {
	fmt.Println("!..Slices are equal..!")
} else {
	fmt.Println("!..Slice are not equal..!")
}

This will output (try it on the Go Playground):

!..Slice are not equal..!
!..Slices are equal..!