Converting single-byte slice to int

[alexs (Alex)]

In my program I need to read data from the byte array, sometimes I need to read single byte, sometimes 2, 4 or 8 bytes. Then these bytes should be converted into “normal” integer values.

For 2, 4 and 8 bytes I can use “encodings/binary” package and its binary.BigEndian.Uint16(), binary.BigEndian.Uint32() and binary.BigEndian.Uint64() and then cast values to int if necessary.

But what is the recommended way to convert single-byte slice to int? I use following code now, but now sure if this is a correct way

import (
    "bytes"
    "encoding/binary"
)

data := []byte{0, 0, 0, 0, 0, 0, 0, 73, 8, 2, 0, 0, 1}
var a byte
err := binary.Read(bytes.NewReader(data[8:9]), binary.BigEndian, &a)
r :=int(a)

Probably there is an unified way to convert slices to integers which works with slices of different length?

[bins (Sebastien Binet)]

It’s correct but rather convoluted.
The big endian and little endian representations of a single byte are the same.
So you could just do:

var r = int(data[8])

[alexs (Alex)]

Thanks!

Is there unified way to convert slice of any length (1, 2, 4, or 8 bytes) to integer? I tried to use
binary.ReadVarint([]byte) but it does not work with single-byte slices. I’m trying to avoid adding condition and different handling inside the loop just for single-byte slices.

[calmh (Jakob Borg)]

You can pad and use Uint64, or you can do it manually: https://play.golang.org/p/eECOVBhWmlH

Note that the results are nonsensical for values over four bytes as int in the playground is 32 bits. Also, sign handling requires consideration.

[alexs (Alex)]

Thanks a lot!