# loop that will output in order from 1 to 5 []bytes in golang

## Issue

How to make a loop that will output in order from 1 to 5 []bytes?

Here is what I need in the output:

``````[0]
[1]
[2]
...
[255]
[0 1]
[1 1]
[2 1]
...
etc (to max 5 bytes)
``````

For example, if I doing a normal loop from numbers and turn them into bytes using these functions:

``````for i := 0; i < 8589934590; i++ {
b : intToBytes(i)
fmt.Println(b)
}

func intToBytes(val int) []byte {
r := make([]byte, 5)
for i := int(0); i < 5; i++ {
r[i] = byte((val >> (8 * i)) & 0xff)
}
return r
}
``````

there will be extra zeros at the end of the output.

If this option is correct, then how to get rid of extra zeros?

## Solution

Here is a solution. Use append to update the byte slice length. Stop when the shifted result is zero.

``````package main

import "fmt"

func intToBytes(val int) []byte {
b := make([]byte, 0, 5)
for i := range b[:cap(b)] {
v := val >> (8 * i)
if v == 0 && i != 0 {
break
}
b = append(b, byte(v))
}
return b
}

func main() {
for i := 0; i < 4; i++ {
b := intToBytes(i)
fmt.Println(b)
}
fmt.Println("...")
for i := 260 - 8; i < 260; i++ {
b := intToBytes(i)
fmt.Println(b)
}
fmt.Println("...")
for i := 8589934590 - 4; i < 8589934590; i++ {
b := intToBytes(i)
fmt.Println(b)
}
}
``````

https://go.dev/play/p/b91oYBpOw_Y

``````[0]
[1]
[2]
[3]
...
[252]
[253]
[254]
[255]
[0 1]
[1 1]
[2 1]
[3 1]
...
[250 255 255 255 1]
[251 255 255 255 1]
[252 255 255 255 1]
[253 255 255 255 1]
``````