Golang : Convert int to byte array([]byte)
Problem :
You need to convert integer variable or constant to byte array ( [] byte ). How to do that?
Solution :
UPDATE: The answer below demonstrates few methods of converting integer variable to []byte
(byte array/slice). The second method should be the answer that you ought to use. Other methods can be useful as well depending on your requirement.
Here you go!
package main
import (
"bytes"
"encoding/binary"
"fmt"
"reflect"
"strconv"
)
func main() {
var intVar = 123
fmt.Println("intVar is : ", intVar)
fmt.Println("intVar type is : ", reflect.TypeOf(intVar))
// depending on what you want to achieve, the first method
// is to split the integer value into individual digit
// i.e 123 to [1,2,3]
// literally ... integer into a byte array of individual digits
var rightMost, tempIntVar int
var byteArray []byte
tempIntVar = intVar
for {
// if use leftMost instead of rightMost, we need to know the length
// of intVar in advance before applying modulo.
// instead of % 10, use % 1e3 , where 3 is the position
// but for simplicity sake and able to handle dynamic intVar length,
// we use rightMost and reverse the order of the slice later.
rightMost = tempIntVar % 10
byteArray = append(byteArray, byte(rightMost)) // convert single digit to byte
// update the tempIntVar, minus the processed rightMost
tempIntVar /= 10
if tempIntVar == 0 {
break
}
}
// need to reverse the order
fixByteArray := []byte{}
for i := range byteArray {
n := byteArray[len(byteArray)-1-i]
fixByteArray = append(fixByteArray, n)
}
//fmt.Println("byteArray : ", byteArray)
fmt.Println("A byte slice for the integer variable.")
fmt.Println("Byte array of integers : ", fixByteArray)
fmt.Printf("Byte array of integers : % x\n", fixByteArray)
fmt.Println("Byte array of integers type is : ", reflect.TypeOf(fixByteArray))
// second method, convert the int directly to []byte
// if you know the machine endian
// for example, LittleEndian
buff := new(bytes.Buffer)
err := binary.Write(buff, binary.LittleEndian, uint16(intVar))
if err != nil {
fmt.Println(err)
}
intByteArray := buff.Bytes()
fmt.Printf("intByteArray : % x\n", intByteArray)
fmt.Println("intByteArray type is : ", reflect.TypeOf(intByteArray))
// verify if 123 translates to 7b correctly
byteI := byte(intVar)
fmt.Printf("%v % x (%T)\n", intVar, byteI, byteI)
// finally, if you just want to
// get the ASCII representation.
// Converting intVar to string first will do the job
intByte := []byte(strconv.Itoa(intVar))
fmt.Println("intByte is : ", intByte)
fmt.Println("intByte in string : ", string(intByte))
fmt.Println("intByte type is : ", reflect.TypeOf(intByte))
}
Output :
intVar is : 123
intVar type is : int
A byte slice for the integer variable.
Byte array of integers : [1 2 3]
Byte array of integers : 01 02 03
Byte array of integers type is : []uint8
intByteArray : 7b 00
intByteArray type is : []uint8
123 7b (uint8)
intByte is : [49 50 51]
intByte in string : 123
intByte type is : []uint8
See also : Golang : convert int to string
By Adam Ng
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