Programming-Idioms

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Idiom #176 Hex string to byte array

From hex string s of 2n digits, build the equivalent array a of n bytes.
Each pair of hexadecimal characters (16 possible values per digit) is decoded into one byte (256 possible values).

const char* hexstring = "deadbeef";
size_t length = sizeof(hexstring);
unsigned char bytearray[length / 2];

for (size_t i = 0, j = 0; i < (length / 2); i++, j += 2)
	bytearray[i] = (hexstring[j] % 32 + 9) % 25 * 16 + (hexstring[j+1] % 32 + 9) % 25;

byte[] a = new byte[s.Length/2];
for (int i = 0, h = 0; h < s.Length; i++, h += 2)
{
  a[i] = (byte) Int32.Parse(s.Substring(h, 2), System.Globalization.NumberStyles.HexNumber);
}
import std.conv;
import std.string;
ubyte[] a = cast(ubyte[]) hexString!s.representation;
import std.algorithms;
import std.array;
import std.conv;
import std.range;
ubyte[] a = s.chunks(2)
             .map!(digits => digits.to!ubyte)
             .array;

  use iso_c_binding, only : c_int8_t
  integer(kind=c_int8_t), dimension(:), allocatable :: a

  allocate (a(len(s)/2))
  read(unit=s,fmt='(*(Z2))') a

import "encoding/hex"
a, err := hex.DecodeString(s)
if err != nil {
	log.Fatal(err)
}
const base = 16
let a = s
  .replace(/../g, '$&_')
  .slice (0, -1)
  .split ('_')
  .map (
    (x) => parseInt (x, base)
  )
$a = array_map('hexdec', str_split($s, 2));
sysutils
for i := 0 to length(s) div 2 - 1 do
  a[i] := StrToInt('$'+Copy(s,2*(i)+1,2));
my @a = split '', pack 'H*', $s;
a = bytearray.fromhex(s)
[s].pack("H*").unpack("C*")
use hex::FromHex
let a: Vec<u8> = Vec::from_hex(s).expect("Invalid Hex String");
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Idiom created by

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Related idioms

const char* hexstring = "deadbeef";
size_t length = sizeof(hexstring);
unsigned char bytearray[length / 2];

for (size_t i = 0, j = 0; i < (length / 2); i++, j += 2)
	bytearray[i] = (hexstring[j] % 32 + 9) % 25 * 16 + (hexstring[j+1] % 32 + 9) % 25;

byte[] a = new byte[s.Length/2];
for (int i = 0, h = 0; h < s.Length; i++, h += 2)
{
  a[i] = (byte) Int32.Parse(s.Substring(h, 2), System.Globalization.NumberStyles.HexNumber);
}
ubyte[] a = cast(ubyte[]) hexString!s.representation;
ubyte[] a = s.chunks(2)
             .map!(digits => digits.to!ubyte)
             .array;

  integer(kind=c_int8_t), dimension(:), allocatable :: a

  allocate (a(len(s)/2))
  read(unit=s,fmt='(*(Z2))') a

a, err := hex.DecodeString(s)
if err != nil {
	log.Fatal(err)
}
const base = 16
let a = s
  .replace(/../g, '$&_')
  .slice (0, -1)
  .split ('_')
  .map (
    (x) => parseInt (x, base)
  )
$a = array_map('hexdec', str_split($s, 2));
for i := 0 to length(s) div 2 - 1 do
  a[i] := StrToInt('$'+Copy(s,2*(i)+1,2));
my @a = split '', pack 'H*', $s;
a = bytearray.fromhex(s)
[s].pack("H*").unpack("C*")
let a: Vec<u8> = Vec::from_hex(s).expect("Invalid Hex String");