UTF-8 encode and decode

From Rosetta Code
Task
UTF-8 encode and decode
You are encouraged to solve this task according to the task description, using any language you may know.

As described in UTF-8 and in Wikipedia, UTF-8 is a popular encoding of (multi-byte) Unicode code-points into eight-bit octets.

The goal of this task is to write a encoder that takes a unicode code-point (an integer representing a unicode character) and returns a sequence of 1-4 bytes representing that character in the UTF-8 encoding.

Then you have to write the corresponding decoder that takes a sequence of 1-4 UTF-8 encoded bytes and return the corresponding unicode character.

Demonstrate the functionality of your encoder and decoder on the following five characters:

Character   Name                                  Unicode    UTF-8 encoding (hex)
---------------------------------------------------------------------------------
A           LATIN CAPITAL LETTER A                U+0041     41
ΓΆ           LATIN SMALL LETTER O WITH DIAERESIS   U+00F6     C3 B6
Π–           CYRILLIC CAPITAL LETTER ZHE           U+0416     D0 96
€           EURO SIGN                             U+20AC     E2 82 AC
π„ž           MUSICAL SYMBOL G CLEF                 U+1D11E    F0 9D 84 9E

Provided below is a reference implementation in Common Lisp.

Common Lisp[edit]

Helper functions

 
(defun ascii-byte-p (octet)
"Return t if octet is a single-byte 7-bit ASCII char.
The most significant bit is 0, so the allowed pattern is 0xxx xxxx."

(assert (typep octet 'integer))
(assert (<= (integer-length octet) 8))
(let ((bitmask #b10000000)
(template #b00000000))
;; bitwise and the with the bitmask #b11000000 to extract the first two bits.
;; check if the first two bits are equal to the template #b10000000.
(= (logand bitmask octet) template)))
 
(defun multi-byte-p (octet)
"Return t if octet is a part of a multi-byte UTF-8 sequence.
The multibyte pattern is 1xxx xxxx. A multi-byte can be either a lead byte or a trail byte."

(assert (typep octet 'integer))
(assert (<= (integer-length octet) 8))
(let ((bitmask #b10000000)
(template #b10000000))
;; bitwise and the with the bitmask #b11000000 to extract the first two bits.
;; check if the first two bits are equal to the template #b10000000.
(= (logand bitmask octet) template)))
 
(defun lead-byte-p (octet)
"Return t if octet is one of the leading bytes of an UTF-8 sequence, nil otherwise.
Allowed leading byte patterns are 0xxx xxxx, 110x xxxx, 1110 xxxx and 1111 0xxx."

(assert (typep octet 'integer))
(assert (<= (integer-length octet) 8))
(let ((bitmasks (list #b10000000 #b11100000 #b11110000 #b11111000))
(templates (list #b00000000 #b11000000 #b11100000 #b11110000)))
(some #'(lambda (a b) (= (logand a octet) b)) bitmasks templates)))
 
(defun n-trail-bytes (octet)
"Take a leading utf-8 byte, return the number of continuation bytes 1-3."
(assert (typep octet 'integer))
(assert (<= (integer-length octet) 8))
(let ((bitmasks (list #b10000000 #b11100000 #b11110000 #b11111000))
(templates (list #b00000000 #b11000000 #b11100000 #b11110000)))
(loop for i from 0 to 3
when (= (nth i templates) (logand (nth i bitmasks) octet))
return i)))
 

Encoder

 
(defun unicode-to-utf-8 (int)
"Take a unicode code point, return a list of one to four UTF-8 encoded bytes (octets)."
(assert (<= (integer-length int) 21))
(let ((n-trail-bytes (cond ((<= #x00000 int #x00007F) 0)
((<= #x00080 int #x0007FF) 1)
((<= #x00800 int #x00FFFF) 2)
((<= #x10000 int #x10FFFF) 3)))
(lead-templates (list #b00000000 #b11000000 #b11100000 #b11110000))
(trail-template #b10000000)
;; number of content bits in the lead byte.
(n-lead-bits (list 7 5 4 3))
;; number of content bits in the trail byte.
(n-trail-bits 6)
;; list to put the UTF-8 encoded bytes in.
(byte-list nil))
(if (= n-trail-bytes 0)
;; if we need 0 trail bytes, ist just an ascii single byte.
(push int byte-list)
(progn
;; if we need more than one byte, first fill the trail bytes with 6 bits each.
(loop for i from 0 to (1- n-trail-bytes)
do (push (+ trail-template
(ldb (byte n-trail-bits (* i n-trail-bits)) int))
byte-list))
;; then copy the remaining content bytes to the lead byte.
(push (+ (nth n-trail-bytes lead-templates)
(ldb (byte (nth n-trail-bytes n-lead-bits) (* n-trail-bytes n-trail-bits)) int))
byte-list)))
;; return the list of UTF-8 encoded bytes.
byte-list))
 

Decoder

 
(defun utf-8-to-unicode (byte-list)
"Take a list of one to four utf-8 encoded bytes (octets), return a code point."
(let ((b1 (car byte-list)))
(cond ((ascii-byte-p b1) b1) ; if a single byte, just return it.
((multi-byte-p b1)
(if (lead-byte-p b1)
(let ((n (n-trail-bytes b1))
;; Content bits we want to extract from each lead byte.
(lead-templates (list #b01111111 #b00011111 #b00001111 #b00000111))
;; Content bits we want to extract from each trail byte.
(trail-template #b00111111))
(if (= n (1- (list-length byte-list)))
;; add lead byte
(+ (ash (logand (nth 0 byte-list) (nth n lead-templates)) (* 6 n))
;; and the trail bytes
(loop for i from 1 to n sum
(ash (logand (nth i byte-list) trail-template) (* 6 (- n i)))))
(error "calculated number of bytes doesnt match the length of the byte list")))
(error "first byte in the list isnt a lead byte"))))))
 

The test

 
(defun test-utf-8 ()
"Return t if the chosen unicode points are encoded and decoded correctly."
(let* ((unicodes-orig (list 65 246 1046 8364 119070))
(unicodes-test (mapcar #'(lambda (x) (utf-8-to-unicode (unicode-to-utf-8 x)))
unicodes-orig)))
(mapcar #'(lambda (x)
(format t
"character ~A, code point: ~6x, utf-8: ~{~x ~}~%"
(code-char x)
x
(unicode-to-utf-8 x)))
unicodes-orig)
;; return t if all are t
(every #'= unicodes-orig unicodes-test)))
 

Test output

 
CL-USER> (test-utf-8)
character A, code point: 41, utf-8: 41
character ΓΆ, code point: F6, utf-8: C3 B6
character Π–, code point: 416, utf-8: D0 96
character €, code point: 20AC, utf-8: E2 82 AC
character π„ž, code point: 1D11E, utf-8: F0 9D 84 9E
T
 


Ada[edit]

Works with: Ada version 2012
with Ada.Strings.Fixed; use Ada.Strings.Fixed;
with Ada.Strings.UTF_Encoding.Wide_Wide_Strings;
with Ada.Integer_Text_IO;
with Ada.Text_IO;
with Ada.Wide_Wide_Text_IO;
 
procedure UTF8_Encode_And_Decode
is
package TIO renames Ada.Text_IO;
package WWTIO renames Ada.Wide_Wide_Text_IO;
package WWS renames Ada.Strings.UTF_Encoding.Wide_Wide_Strings;
 
function To_Hex
(i : in Integer;
width : in Natural := 0;
fill : in Character := '0') return String
is
holder : String(1 .. 20);
begin
Ada.Integer_Text_IO.Put(holder, i, 16);
declare
hex : constant String := holder(Index(holder, "#")+1 .. holder'Last-1);
filled : String := Natural'Max(width, hex'Length) * fill;
begin
filled(filled'Last - hex'Length + 1 .. filled'Last) := hex;
return filled;
end;
end To_Hex;
 
input : constant Wide_Wide_String := "AΓΆΠ–β‚¬π„ž";
begin
TIO.Put_Line("Character Unicode UTF-8 encoding (hex)");
TIO.Put_Line(43 * '-');
for WWC of input loop
WWTIO.Put(WWC & " ");
declare
filled : String := 11 * ' ';
unicode : constant String := "U+" & To_Hex(Wide_Wide_Character'Pos(WWC), width => 4);
utf8_string : constant String := WWS.Encode((1 => WWC));
begin
filled(filled'First .. filled'First + unicode'Length - 1) := unicode;
TIO.Put(filled);
for C of utf8_string loop
TIO.Put(To_Hex(Character'Pos(C)) & " ");
end loop;
TIO.New_Line;
end;
end loop;
end UTF8_Encode_And_Decode;
Output:
Character   Unicode    UTF-8 encoding (hex)
-------------------------------------------
A           U+0041     41 
ΓΆ           U+00F6     C3 B6 
Π–           U+0416     D0 96 
€           U+20AC     E2 82 AC 
π„ž           U+1D11E    F0 9D 84 9E 

C[edit]

 
#include <stdio.h>
#include <stdlib.h>
#include <inttypes.h>
 
typedef struct {
char mask; /* char data will be bitwise AND with this */
char lead; /* start bytes of current char in utf-8 encoded character */
uint32_t beg; /* beginning of codepoint range */
uint32_t end; /* end of codepoint range */
int bits_stored; /* the number of bits from the codepoint that fits in char */
}utf_t;
 
utf_t * utf[] = {
/* mask lead beg end bits */
[0] = &(utf_t){0b00111111, 0b10000000, 0, 0, 6 },
[1] = &(utf_t){0b01111111, 0b00000000, 0000, 0177, 7 },
[2] = &(utf_t){0b00011111, 0b11000000, 0200, 03777, 5 },
[3] = &(utf_t){0b00001111, 0b11100000, 04000, 0177777, 4 },
[4] = &(utf_t){0b00000111, 0b11110000, 0200000, 04177777, 3 },
&(utf_t){0},
};
 
/* All lengths are in bytes */
int codepoint_len(const uint32_t cp); /* len of associated utf-8 char */
int utf8_len(const char ch); /* len of utf-8 encoded char */
 
char *to_utf8(const uint32_t cp);
uint32_t to_cp(const char chr[4]);
 
int codepoint_len(const uint32_t cp)
{
int len = 0;
for(utf_t **u = utf; *u; ++u) {
if((cp >= (*u)->beg) && (cp <= (*u)->end)) {
break;
}
++len;
}
if(len > 4) /* Out of bounds */
exit(1);
 
return len;
}
 
int utf8_len(const char ch)
{
int len = 0;
for(utf_t **u = utf; *u; ++u) {
if((ch & ~(*u)->mask) == (*u)->lead) {
break;
}
++len;
}
if(len > 4) { /* Malformed leading byte */
exit(1);
}
return len;
}
 
char *to_utf8(const uint32_t cp)
{
static char ret[5];
const int bytes = codepoint_len(cp);
 
int shift = utf[0]->bits_stored * (bytes - 1);
ret[0] = (cp >> shift & utf[bytes]->mask) | utf[bytes]->lead;
shift -= utf[0]->bits_stored;
for(int i = 1; i < bytes; ++i) {
ret[i] = (cp >> shift & utf[0]->mask) | utf[0]->lead;
shift -= utf[0]->bits_stored;
}
ret[bytes] = '\0';
return ret;
}
 
uint32_t to_cp(const char chr[4])
{
int bytes = utf8_len(*chr);
int shift = utf[0]->bits_stored * (bytes - 1);
uint32_t codep = (*chr++ & utf[bytes]->mask) << shift;
 
for(int i = 1; i < bytes; ++i, ++chr) {
shift -= utf[0]->bits_stored;
codep |= ((char)*chr & utf[0]->mask) << shift;
}
 
return codep;
}
 
int main(void)
{
const uint32_t *in, input[] = {0x0041, 0x00f6, 0x0416, 0x20ac, 0x1d11e, 0x0};
 
printf("Character Unicode UTF-8 encoding (hex)\n");
printf("----------------------------------------\n");
 
char *utf8;
uint32_t codepoint;
for(in = input; *in; ++in) {
utf8 = to_utf8(*in);
codepoint = to_cp(utf8);
printf("%s U+%-7.4x", utf8, codepoint);
 
for(int i = 0; utf8[i] && i < 4; ++i) {
printf("%hhx ", utf8[i]);
}
printf("\n");
}
return 0;
}
 

Output

 
Character Unicode UTF-8 encoding (hex)
----------------------------------------
A U+0041 41
ΓΆ U+00f6 c3 b6
Π– U+0416 d0 96
€ U+20ac e2 82 ac
π„ž U+1d11e f0 9d 84 9e
 
 

D[edit]

import std.conv;
import std.stdio;
 
immutable CHARS = ["A","ΓΆ","Π–","€","π„ž"];
 
void main() {
writeln("Character Code-Point Code-Units");
foreach (c; CHARS) {
auto bytes = cast(ubyte[]) c; //The raw bytes of a character can be accessed by casting
auto unicode = cast(uint) to!dstring(c)[0]; //Convert from a UTF8 string to a UTF32 string, and cast the first character to a number
writefln("%s  %7X [%(%X, %)]", c, unicode, bytes);
}
}
Output:
Character   Code-Point   Code-Units
A                   41   [41]
ΓΆ                   F6   [C3, B6]
Π–                  416   [D0, 96]
€                 20AC   [E2, 82, AC]
π„ž                1D11E   [F0, 9D, 84, 9E]

Elena[edit]

ELENA 4.x :

import system'routines;
import extensions;
 
extension op : String
{
string printAsString()
{
console.print(self," ")
}
 
string printAsUTF8Array()
{
self.toByteArray().forEach:(b){ console.print(b.toString(16)," ") }
}
 
string printAsUTF32()
{
self.toArray().forEach:(c){ console.print("U+",c.toInt().toString(16)," ") }
}
}
 
public program()
{
"A".printAsString().printAsUTF8Array().printAsUTF32();
console.printLine();
 
"ΓΆ".printAsString().printAsUTF8Array().printAsUTF32();
console.printLine();
 
"Π–".printAsString().printAsUTF8Array().printAsUTF32();
console.printLine();
 
"€".printAsString().printAsUTF8Array().printAsUTF32();
console.printLine();
 
"π„ž".printAsString().printAsUTF8Array().printAsUTF32();
console.printLine();
}
Output:
A 41 U+41 
ΓΆ C3 B6 U+F6 
Π– D0 96 U+416 
€ E2 82 AC U+20AC 
π„ž F0 9D 84 9E U+1D11E

F#[edit]

 
// Unicode character point to UTF8. Nigel Galloway: March 19th., 2018
let fN g = match List.findIndex (fun n->n>g) [0x80;0x800;0x10000;0x110000] with
|0->[g]
|1->[0xc0+(g&&&0x7c0>>>6);0x80+(g&&&0x3f)]
|2->[0xe0+(g&&&0xf000>>>12);0x80+(g&&&0xfc0>>>6);0x80+(g&&&0x3f)]
|_->[0xf0+(g&&&0x1c0000>>>18);0x80+(g&&&0x3f000>>>12);0x80+(g&&&0xfc0>>>6);0x80+(g&&&0x3f)]
 
Output:
for n in fN 0x41    do printf "%x " n -> 41
for n in fN 0xf6    do printf "%x " n -> c3 b6 
for n in fN 0x416   do printf "%x " n -> d0 96 
for n in fN 0x20ac  do printf "%x " n -> e2 82 ac 
for n in fN 0x1d11e do printf "%x " n -> f0 9d 84 9e 

Go[edit]

Implementation[edit]

This implementation is missing all checks for invalid data and so is not production-ready, but illustrates the basic UTF-8 encoding scheme.

package main
 
import (
"bytes"
"encoding/hex"
"fmt"
"log"
"strings"
)
 
var testCases = []struct {
rune
string
}{
{'A', "41"},
{'ΓΆ', "C3 B6"},
{'Π–', "D0 96"},
{'€', "E2 82 AC"},
{'π„ž', "F0 9D 84 9E"},
}
 
func main() {
for _, tc := range testCases {
// derive some things from test data
u := fmt.Sprintf("U+%04X", tc.rune)
b, err := hex.DecodeString(strings.Replace(tc.string, " ", "", -1))
if err != nil {
log.Fatal("bad test data")
}
// exercise encoder and decoder on test data
e := encodeUTF8(tc.rune)
d := decodeUTF8(b)
// show function return values
fmt.Printf("%c  %-7s  %X\n", d, u, e)
// validate return values against test data
if !bytes.Equal(e, b) {
log.Fatal("encodeUTF8 wrong")
}
if d != tc.rune {
log.Fatal("decodeUTF8 wrong")
}
}
}
 
const (
// first byte of a 2-byte encoding starts 110 and carries 5 bits of data
b2Lead = 0xC0 // 1100 0000
b2Mask = 0x1F // 0001 1111
 
// first byte of a 3-byte encoding starts 1110 and carries 4 bits of data
b3Lead = 0xE0 // 1110 0000
b3Mask = 0x0F // 0000 1111
 
// first byte of a 4-byte encoding starts 11110 and carries 3 bits of data
b4Lead = 0xF0 // 1111 0000
b4Mask = 0x07 // 0000 0111
 
// non-first bytes start 10 and carry 6 bits of data
mbLead = 0x80 // 1000 0000
mbMask = 0x3F // 0011 1111
)
 
func encodeUTF8(r rune) []byte {
switch i := uint32(r); {
case i <= 1<<7-1: // max code point that encodes into a single byte
return []byte{byte(r)}
case i <= 1<<11-1: // into two bytes
return []byte{
b2Lead | byte(r>>6),
mbLead | byte(r)&mbMask}
case i <= 1<<16-1: // three
return []byte{
b3Lead | byte(r>>12),
mbLead | byte(r>>6)&mbMask,
mbLead | byte(r)&mbMask}
default:
return []byte{
b4Lead | byte(r>>18),
mbLead | byte(r>>12)&mbMask,
mbLead | byte(r>>6)&mbMask,
mbLead | byte(r)&mbMask}
}
}
 
func decodeUTF8(b []byte) rune {
switch b0 := b[0]; {
case b0 < 0x80:
return rune(b0)
case b0 < 0xE0:
return rune(b0&b2Mask)<<6 |
rune(b[1]&mbMask)
case b0 < 0xF0:
return rune(b0&b3Mask)<<12 |
rune(b[1]&mbMask)<<6 |
rune(b[2]&mbMask)
default:
return rune(b0&b4Mask)<<18 |
rune(b[1]&mbMask)<<12 |
rune(b[2]&mbMask)<<6 |
rune(b[3]&mbMask)
}
}
Output:
A  U+0041   41
ΓΆ  U+00F6   C3B6
Π–  U+0416   D096
€  U+20AC   E282AC
π„ž  U+1D11E  F09D849E

Library/language[edit]

package main
 
import (
"fmt"
"unicode/utf8"
)
 
func utf8encode(codepoint rune) []byte {
buffer := make([]byte, 4)
length := utf8.EncodeRune(buffer, codepoint)
return buffer[:length]
}
 
func utf8decode(bytes []byte) rune {
result, _ := utf8.DecodeRune(bytes)
return result
}
 
func main() {
fmt.Printf("%-7s %7s\t%s\t%s\n", "Char", "Unicode", "UTF-8 encoded", "Decoded");
for _, codepoint := range []rune{'A', 'ΓΆ', 'Π–', '€', 'π„ž'} {
encoded := utf8encode(codepoint)
decoded := utf8decode(encoded)
fmt.Printf("%-7c U+%04X\t%-12X\t%c\n", codepoint, codepoint, encoded, decoded)
}
}
Output:
Char    Unicode	UTF-8 encoded	Decoded
A       U+0041	41          	A
ΓΆ       U+00F6	C3B6        	ΓΆ
Π–       U+0416	D096        	Π–
€       U+20AC	E282AC      	€
π„ž       U+1D11E	F09D849E    	π„ž

Alternately:

package main
 
import (
"fmt"
)
 
func utf8encode(codepoint rune) []byte {
return []byte(string([]rune{codepoint}))
}
 
func utf8decode(bytes []byte) rune {
return []rune(string(bytes))[0]
}
 
func main() {
fmt.Printf("%-7s %7s\t%s\t%s\n", "Char", "Unicode", "UTF-8 encoded", "Decoded");
for _, codepoint := range []rune{'A', 'ΓΆ', 'Π–', '€', 'π„ž'} {
encoded := utf8encode(codepoint)
decoded := utf8decode(encoded)
fmt.Printf("%-7c U+%04X\t%-12X\t%c\n", codepoint, codepoint, encoded, decoded)
}
}
Output:
Char    Unicode	UTF-8 encoded	Decoded
A       U+0041	41          	A
ΓΆ       U+00F6	C3B6        	ΓΆ
Π–       U+0416	D096        	Π–
€       U+20AC	E282AC      	€
π„ž       U+1D11E	F09D849E    	π„ž

Haskell[edit]

Example makes use of bytestring and text packages:

module Main (main) where
 
import qualified Data.ByteString as ByteString (pack, unpack)
import Data.Char (chr, ord)
import Data.Foldable (for_)
import Data.List (intercalate)
import qualified Data.Text as Text (head, singleton)
import qualified Data.Text.Encoding as Text (decodeUtf8, encodeUtf8)
import Text.Printf (printf)
 
encodeCodepoint :: Int -> [Int]
encodeCodepoint = map fromIntegral . ByteString.unpack . Text.encodeUtf8 . Text.singleton . chr
 
decodeToCodepoint :: [Int] -> Int
decodeToCodepoint = ord . Text.head . Text.decodeUtf8 . ByteString.pack . map fromIntegral
 
main :: IO ()
main = do
putStrLn "Character Unicode UTF-8 encoding (hex) Decoded"
putStrLn "-------------------------------------------------"
for_ [0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E] $ \codepoint -> do
let values = encodeCodepoint codepoint
codepoint' = decodeToCodepoint values
putStrLn $ printf "%c  %-7s  %-20s  %c"
codepoint
(printf "U+%04X" codepoint :: String)
(intercalate " " (map (printf "%02X") values))
codepoint'
Output:
Character  Unicode  UTF-8 encoding (hex)  Decoded
-------------------------------------------------
A          U+0041   41                    A
ΓΆ          U+00F6   C3 B6                 ΓΆ
Π–          U+0416   D0 96                 Π–
€          U+20AC   E2 82 AC              €
π„ž          U+1D11E  F0 9D 84 9E           π„ž

J[edit]

Solution:

utf8=: 8&u:               NB. converts to UTF-8 from unicode or unicode codepoint integer
ucp=: 9&u: NB. converts to unicode from UTF-8 or unicode codepoint integer
ucp_hex=: [email protected](3 u: ucp) NB. converts to unicode codepoint hexadecimal from UTF-8, unicode or unicode codepoint integer

Examples:

   utf8 65 246 1046 8364 119070
AΓΆΠ–β‚¬π„ž
ucp 65 246 1046 8364 119070
AΓΆΠ–β‚¬π„ž
ucp 'AΓΆΠ–β‚¬π„ž'
AΓΆΠ–β‚¬π„ž
utf8 ucp 65 246 1046 8364 119070
AΓΆΠ–β‚¬π„ž
ucp_hex utf8 65 246 1046 8364 119070
00041
000f6
00416
020ac
1d11e
[email protected] ucp_hex utf8 65 246 1046 8364 119070
AΓΆΠ–β‚¬π„ž

Java[edit]

Works with: Java version 7+
import java.nio.charset.StandardCharsets;
import java.util.Formatter;
 
public class UTF8EncodeDecode {
 
public static byte[] utf8encode(int codepoint) {
return new String(new int[]{codepoint}, 0, 1).getBytes(StandardCharsets.UTF_8);
}
 
public static int utf8decode(byte[] bytes) {
return new String(bytes, StandardCharsets.UTF_8).codePointAt(0);
}
 
public static void main(String[] args) {
System.out.printf("%-7s %-43s %7s\t%s\t%7s%n",
"Char", "Name", "Unicode", "UTF-8 encoded", "Decoded");
 
for (int codepoint : new int[]{0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E}) {
byte[] encoded = utf8encode(codepoint);
Formatter formatter = new Formatter();
for (byte b : encoded) {
formatter.format("%02X ", b);
}
String encodedHex = formatter.toString();
int decoded = utf8decode(encoded);
System.out.printf("%-7c %-43s U+%04X\t%-12s\tU+%04X%n",
codepoint, Character.getName(codepoint), codepoint, encodedHex, decoded);
}
}
}
Output:
Char    Name                                        Unicode	UTF-8 encoded	Decoded
A       LATIN CAPITAL LETTER A                      U+0041	41          	A
ΓΆ       LATIN SMALL LETTER O WITH DIAERESIS         U+00F6	C3 B6       	ΓΆ
Π–       CYRILLIC CAPITAL LETTER ZHE                 U+0416	D0 96       	Π–
€       EURO SIGN                                   U+20AC	E2 82 AC    	€
π„ž      MUSICAL SYMBOL G CLEF                       U+1D11E	F0 9D 84 9E 	π„ž

JavaScript[edit]

An implementation in ECMAScript 2015 (ES6):

 
/***************************************************************************\
|* Pure UTF-8 handling without detailed error reporting functionality. *|
|***************************************************************************|
|* utf8encode *|
|* < String character or UInt32 code point *|
|* > Uint8Array encoded_character *|
|* | ErrorString *|
|* *|
|* utf8encode takes a string or uint32 representing a single code point *|
|* as its argument and returns an array of length 1 up to 4 containing *|
|* utf8 code units representing that character. *|
|***************************************************************************|
|* utf8decode *|
|* < Unit8Array [highendbyte highmidendbyte lowmidendbyte lowendbyte] *|
|* > uint32 character *|
|* | ErrorString *|
|* *|
|* utf8decode takes an array of one to four uint8 representing utf8 code *|
|* units and returns a uint32 representing that code point. *|
\***************************************************************************/

 
const
utf8encode=
n=>
(m=>
m<0x80
?Uint8Array.from(
[ m>>0&0x7f|0x00])
:m<0x800
?Uint8Array.from(
[ m>>6&0x1f|0xc0,m>>0&0x3f|0x80])
:m<0x10000
?Uint8Array.from(
[ m>>12&0x0f|0xe0,m>>6&0x3f|0x80,m>>0&0x3f|0x80])
:m<0x110000
?Uint8Array.from(
[ m>>18&0x07|0xf0,m>>12&0x3f|0x80,m>>6&0x3f|0x80,m>>0&0x3f|0x80])
:(()=>{throw'Invalid Unicode Code Point!'})())
( typeof n==='string'
?n.codePointAt(0)
:n&0x1fffff),
utf8decode=
([m,n,o,p])=>
m<0x80
?( m&0x7f)<<0
:0xc1<m&&m<0xe0&&n===(n&0xbf)
?( m&0x1f)<<6|( n&0x3f)<<0
:( m===0xe0&&0x9f<n&&n<0xc0
||0xe0<m&&m<0xed&&0x7f<n&&n<0xc0
||m===0xed&&0x7f<n&&n<0xa0
||0xed<m&&m<0xf0&&0x7f<n&&n<0xc0)
&&o===o&0xbf
?( m&0x0f)<<12|( n&0x3f)<<6|( o&0x3f)<<0
:( m===0xf0&&0x8f<n&&n<0xc0
||m===0xf4&&0x7f<n&&n<0x90
||0xf0<m&&m<0xf4&&0x7f<n&&n<0xc0)
&&o===o&0xbf&&p===p&0xbf
?( m&0x07)<<18|( n&0x3f)<<12|( o&0x3f)<<6|( p&0x3f)<<0
:(()=>{throw'Invalid UTF-8 encoding!'})()
 

The testing inputs:

 
const
str=
'AΓΆΠ–β‚¬π„ž'
,cps=
Uint32Array.from(str,s=>s.codePointAt(0))
,cus=
[ [ 0x41]
,[ 0xc3,0xb6]
,[ 0xd0,0x96]
,[ 0xe2,0x82,0xac]
,[ 0xf0,0x9d,0x84,0x9e]]
.map(a=>Uint8Array.from(a))
,zip3=
([a,...as],[b,...bs],[c,...cs])=>
0<as.length+bs.length+cs.length
?[ [ a,b,c],...zip3(as,bs,cs)]
:[ [ a,b,c]]
,inputs=zip3(str,cps,cus);
 

The testing code:

 
console.log(`\
${'Character'.padEnd(16)}\
${'CodePoint'.padEnd(16)}\
${'CodeUnits'.padEnd(16)}\
${'uft8encode(ch)'.padEnd(16)}\
${'uft8encode(cp)'.padEnd(16)}\
utf8decode(cu)`)
for(let [ch,cp,cu] of inputs)
console.log(`\
${ch.padEnd(16)}\
${cp.toString(0x10).padStart(8,'U+000000').padEnd(16)}\
${`[${[...cu].map(n=>n.toString(0x10))}]`.padEnd(16)}\
${`[${[...utf8encode(ch)].map(n=>n.toString(0x10))}]`.padEnd(16)}\
${`[${[...utf8encode(cp)].map(n=>n.toString(0x10))}]`.padEnd(16)}\
${utf8decode(cu).toString(0x10).padStart(8,'U+000000')}`)
 

and finally, the output from the test:

Character       CodePoint       CodeUnits       uft8encode(ch)  uft8encode(cp)  utf8decode(cu)
A               U+000041        [41]            [41]            [41]            U+000041
ΓΆ               U+0000f6        [c3,b6]         [c3,b6]         [c3,b6]         U+0000f6
Π–               U+000416        [d0,96]         [d0,96]         [d0,96]         U+000416
€               U+0020ac        [e2,82,ac]      [e2,82,ac]      [e2,82,ac]      U+0020ac
π„ž              U+01d11e        [f0,9d,84,9e]   [f0,9d,84,9e]   [f0,9d,84,9e]   U+01d11e
Note that the misalign there on the last line is caused by the string length of astral characters being 2 so the padding functions break.

Julia[edit]

Works with: Julia version 0.6

Julia supports by default UTF-8 encoding.

for t in ("A", "ΓΆ", "Π–", "€", "π„ž")
enc = Vector{UInt8}(t)
dec = String(enc)
println(dec, " β†’ ", enc)
end
Output:
A β†’ UInt8[0x41]
ΓΆ β†’ UInt8[0xc3, 0xb6]
Π– β†’ UInt8[0xd0, 0x96]
€ β†’ UInt8[0xe2, 0x82, 0xac]
π„ž β†’ UInt8[0xf0, 0x9d, 0x84, 0x9e]

Kotlin[edit]

// version 1.1.2
 
fun utf8Encode(codePoint: Int) = String(intArrayOf(codePoint), 0, 1).toByteArray(Charsets.UTF_8)
 
fun utf8Decode(bytes: ByteArray) = String(bytes, Charsets.UTF_8).codePointAt(0)
 
fun main(args: Array<String>) {
val codePoints = intArrayOf(0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E)
println("Char Name Unicode UTF-8 Decoded")
for (codePoint in codePoints) {
var n = if(codePoint <= 0xFFFF) 4 else 5
System.out.printf("%-${n}c  %-35s U+%05X ", codePoint, Character.getName(codePoint), codePoint)
val bytes = utf8Encode(codePoint)
var s = ""
for (byte in bytes) s += "%02X ".format(byte)
val decoded = utf8Decode(bytes)
n = if(decoded.toInt() <= 0xFFFF) 12 else 11
System.out.printf("%-${n}s  %c\n", s, decoded)
}
}
Output:
Char  Name                                 Unicode  UTF-8         Decoded
A     LATIN CAPITAL LETTER A               U+00041  41            A
ΓΆ     LATIN SMALL LETTER O WITH DIAERESIS  U+000F6  C3 B6         ΓΆ
Π–     CYRILLIC CAPITAL LETTER ZHE          U+00416  D0 96         Π–
€     EURO SIGN                            U+020AC  E2 82 AC      €
π„ž     MUSICAL SYMBOL G CLEF                U+1D11E  F0 9D 84 9E   π„ž

Lingo[edit]

Since UTF-8 is Lingo's native string encoding, and UTF-8 strings can be read into byteArrays (and v.v.), such UTF-8 encoding and decoding is built-in.
Relevant Lingo functions are:
- charToNum (string): converts single-character string to unicode code point (int)
- numToChar (int): converts unicode code point (int) to single-character string
- byteArray (string): creates byte array of UTF-8 bytes for string
- byteArray.toHexString (intStart, intLen): returns hex string representation of byte array (e.g. for printing)
- byteArray.readRawString (intLen, [strCharSet="UTF-8"]): reads a fixed number of bytes as a string

chars = ["A", "ΓΆ", "Π–", "€", "π„ž"]
put "Character Unicode (int) UTF-8 (hex) Decoded"
repeat with c in chars
ba = bytearray(c)
put col(c, 12) & col(charToNum(c), 16) & col(ba.toHexString(1, ba.length), 14) & ba.readRawString(ba.length)
end repeat

Helper function for table formatting

on col (val, len)
str = string(val)
repeat with i = str.length+1 to len
put " " after str
end repeat
return str
end
Output:
Character   Unicode (int)   UTF-8 (hex)   Decoded
A           65              41            A
ΓΆ           246             c3 b6         ΓΆ
Π–           1046            d0 96         Π–
€           8364            e2 82 ac      €
π„ž           119070          f0 9d 84 9e   π„ž

Lua[edit]

Works with: Lua version 5.3
 
-- Accept an integer representing a codepoint.
-- Return the values of the individual octets.
function encode (codepoint)
local codepoint_str = utf8.char(codepoint)
local result = {}
 
for i = 1, #codepoint_str do
result[#result + 1] = string.unpack("B", codepoint_str, i)
end
 
return table.unpack(result)
end
 
-- Accept a variable number of octets.
-- Return the corresponding Unicode character.
function decode (...)
local len = select("#", ...) -- the number of octets
local fmt = string.rep("B", len)
 
return string.pack(fmt, ...)
end
 
-- Run the given test cases.
function test_encode_decode ()
-- "A", "ΓΆ", "Π–", "€", "π„ž"
local tests = {tonumber("41", 16), tonumber("f6", 16), tonumber("416", 16),
tonumber("20ac", 16), tonumber("1d11e", 16)}
 
for i, test in ipairs(tests) do
print("Char: ", test)
print("Encoding: ", encode(test))
print("Decoding: ", decode(encode(test)))
end
end
 
Output:
Char: 	65
Encoding: 	65
Decoding: 	A
Char: 	246
Encoding: 	195	182
Decoding: 	ΓΆ
Char: 	1046
Encoding: 	208	150
Decoding: 	Π–
Char: 	8364
Encoding: 	226	130	172
Decoding: 	€
Char: 	119070
Encoding: 	240	157	132	158
Decoding: 	π„ž

M2000 Interpreter[edit]

 
Module EncodeDecodeUTF8 {
a$=string$("Hello" as UTF8enc)
Print Len(A$)=2.5 ' 2.5 words=5 bytes
b$=string$(a$ as UTF8dec)
Print b$
Print Len(b$)=5 ' 5 words = 10 bytes
 
Print Len(string$("A" as UTF8enc))=.5 ' 1 byte
Print Len(string$("ΓΆ" as UTF8enc))=1 ' 2 bytes
Print Len(string$("Π–" as UTF8enc))=1 ' 2 bytes
Print Len(string$("€" as UTF8enc))=1.5 ' 3 bytes
Print Len(string$("π„ž" as UTF8enc))=2 '4 bytes
a$=string$("π„ž" as UTF8enc)
Buffer Bytes as Byte*4
Return Bytes, 0:=a$
\\ F0 9D 84 9E
Hex Eval(bytes, 0), Eval(bytes, 1), Eval(bytes, 2), Eval(bytes, 3)
}
EncodeDecodeUTF8
 
Output:
      True
Hello
      True
      True
      True
      True
      True
      True
    0x00F0    0x009D    0x0084    0x009E

Mathematica[edit]

utf = ToCharacterCode[ToString["AâЖ€", CharacterEncoding -> "UTF8"]]
ToCharacterCode[FromCharacterCode[utf, "UTF8"]]
Output:
{65, 195, 182, 208, 150, 226, 130, 172}
{65, 246, 1046, 8364}

Perl[edit]

#!/usr/bin/perl
use strict;
use warnings;
use Unicode::UCD 'charinfo'; # getting the unicode name of the character
use utf8; # using non-ascii-characters in source code
binmode STDOUT, ":encoding(UTF-8)"; # printing non-ascii-characters to screen
 
my @chars = map {ord} qw/A ΓΆ Π– € π„ž/; # @chars contains the unicode points
my $print_format = '%5s  %-35s';
printf "$print_format %8s  %s\n" , 'char', 'name', 'unicode', 'utf-8 encoding';
map{
my $name = charinfo($_)->{'name'}; # get unicode name
printf "$print_format  %06x " , chr, lc $name, $_;
my $utf8 = chr; # single char (using implicit $_)
utf8::encode($utf8); # inplace encoding into utf8 parts
map{ # for each utf8 char print ord
printf " %x", ord;
} split //, $utf8;
print "\n";
} @chars;
Output:
 char  name                                 unicode  utf-8 encoding
    A  latin capital letter a               000041   41
    ΓΆ  latin small letter o with diaeresis  0000f6   c3 b6
    Π–  cyrillic capital letter zhe          000416   d0 96
    €  euro sign                            0020ac   e2 82 ac
    π„ž  musical symbol g clef                01d11e   f0 9d 84 9e

Perl 6[edit]

Works with: Rakudo version 2017.02

Pretty much all built in to the language.

say sprintf("%-18s %-36s|%8s| %7s |%14s | %s\n", 'Character|', 'Name', 'Ordinal', 'Unicode', 'UTF-8 encoded', 'decoded'), '-' x 100;
 
for < A ΓΆ Π– € π„ž 😜 πŸ‘¨β€πŸ‘©β€πŸ‘§β€πŸ‘¦> -> $char {
printf "  %-5s | %-43s | %6s | %-7s | %12s |%4s\n", $char, $char.uninames.join(','), $char.ords.join(' '),
('U+' X~ $char.ordsΒ».base(16)).join(' '), $char.encode('UTF8').listΒ».base(16).Str, $char.encode('UTF8').decode;
}
Output:
Character|         Name                                | Ordinal| Unicode | UTF-8 encoded | decoded
----------------------------------------------------------------------------------------------------
   A     | LATIN CAPITAL LETTER A                      |     65 | U+41    |           41  |   A
   ΓΆ     | LATIN SMALL LETTER O WITH DIAERESIS         |    246 | U+F6    |        C3 B6  |   ΓΆ
   Π–    | CYRILLIC CAPITAL LETTER ZHE                 |   1046 | U+416   |        D0 96  |   Π–
   €     | EURO SIGN                                   |   8364 | U+20AC  |     E2 82 AC  |   €
   π„ž     | MUSICAL SYMBOL G CLEF                       | 119070 | U+1D11E |  F0 9D 84 9E  |   π„ž
   😜    | FACE WITH STUCK-OUT TONGUE AND WINKING EYE  | 128540 | U+1F61C |  F0 9F 98 9C  |   😜
   πŸ‘¨β€πŸ‘©β€πŸ‘§β€πŸ‘¦    | MAN,ZERO WIDTH JOINER,WOMAN,ZERO WIDTH JOINER,GIRL,ZERO WIDTH JOINER,BOY | 128104 8205 128105 8205 128103 8205 128102 | U+1F468 U+200D U+1F469 U+200D U+1F467 U+200D U+1F466 | F0 9F 91 A8 E2 80 8D F0 9F 91 A9 E2 80 8D F0 9F 91 A7 E2 80 8D F0 9F 91 A6  |   πŸ‘¨β€πŸ‘©β€πŸ‘§β€πŸ‘¦

Phix[edit]

Standard autoinclude, see the manual and/or builtins/utfconv.e ( http://phix.x10.mx/docs/html/utfconv.htm and/or https://bitbucket.org/petelomax/phix/src )
As requested in the task description:

constant tests = {#0041, #00F6, #0416, #20AC, #1D11E}
 
function hex(sequence s, string fmt) -- output helper
for i=1 to length(s) do
s[i] = sprintf(fmt,s[i])
end for
return join(s,',')
end function
 
for i=1 to length(tests) do
integer codepoint = tests[i]
sequence s = utf32_to_utf8({codepoint}),
r = utf8_to_utf32(s)
printf(1,"#%04x -> {%s} -> {%s}\n",{codepoint, hex(s,"#%02x"),hex(r,"#%04x")})
end for
Output:
#0041 -> {#41} -> {#0041}
#00F6 -> {#C3,#B6} -> {#00F6}
#0416 -> {#D0,#96} -> {#0416}
#20AC -> {#E2,#82,#AC} -> {#20AC}
#1D11E -> {#F0,#9D,#84,#9E} -> {#1D11E}

PureBasic[edit]

The encoding and decoding procedure are kept simple and designed to work with an array of 5 elements for input/output of the UTF-8 encoding for a single code point at a time. It was decided not to use a more elaborate example that would have been able to operate on a buffer to encode/decode more than one code point at a time.

#UTF8_codePointMaxByteCount = 4 ;UTF-8 encoding uses only a maximum of 4 bytes to encode a codepoint
 
Procedure UTF8_encode(x, Array encoded_codepoint.a(1)) ;x is codepoint to encode, the array will contain output
;Array encoded_codepoint() is used for output.
;After encode element zero holds the count of significant bytes in elements 1 to 4
If ArraySize(encoded_codepoint()) < #UTF8_codePointMaxByteCount
ReDim encoded_codepoint.a(#UTF8_codePointMaxByteCount)
EndIf
 
Select x
Case 0 To $7F
encoded_codepoint(0) = 1
encoded_codepoint(1) = x ;all 7 bits
Case $80 To $7FF
encoded_codepoint(0) = 2
encoded_codepoint(2) = (x & %00111111) | %10000000 ;lowest 6 bits
encoded_codepoint(1) = (x >> 6) | %11000000 ;highest bits 7 -> 11
Case $800 To $FFFF
encoded_codepoint(0) = 3
encoded_codepoint(3) = (x & %00111111) | %10000000 ;lowest 6 bits
encoded_codepoint(2) = ((x >> 6) & %00111111) | %10000000 ;bits 7 -> 12
encoded_codepoint(1) = (x >> 12) | %11100000 ;highest bits 13 -> 16
 
Case $10000 To $10FFFF
encoded_codepoint(0) = 4
encoded_codepoint(4) = (x & %00111111) | %10000000 ;lowest 6 bits
encoded_codepoint(3) = ((x >> 6) & %00111111) | %10000000 ;bits 7 -> 12
encoded_codepoint(2) = ((x >> 12) & %00111111) | %10000000 ;bits 13 -> 18
encoded_codepoint(1) = (x >> 18) | %11110000 ;highest bits 19 -> 21
Default
encoded_codepoint(0) = 0 ;error, codepoint is not valid and can't be encoded
EndSelect
EndProcedure
 
Procedure UTF8_decode(Array encoded_codepoint.a(1))
;Array encoded_codepoint() holds the UTF-8 encoding in elements 1 to 4, element zero isn't used for decoding.
Protected x = -1 ;initialzie with error value for possible improper encoding
 
If ArraySize(encoded_codepoint()) < #UTF8_codePointMaxByteCount
ProcedureReturn x ;Input array was not dimensioned properly.
EndIf
 
;Determine the number of bytes in the UTF8 encoding by looking at first byte
;and then proceeding accordingly.
Select encoded_codepoint(1)
Case %00000000 To %01111111 ;1 byte encoding
x = encoded_codepoint(1)
Case %11000000 To %11011111 ;2 byte encoding
x = (encoded_codepoint(1) & %00011111) << 6 ;last 5 bits only
x | (encoded_codepoint(2) & %00111111)
Case %11100000 To %11101111 ;3 byte encoding
x = (encoded_codepoint(1) & %00001111) << 6 ;last 4 bits only
x << 6 + (encoded_codepoint(2) & %00111111)
x << 6 + (encoded_codepoint(3) & %00111111)
Case %11110000 To %11110111 ;4 byte encoding
x = (encoded_codepoint(1) & %00000111) << 6 ;last 3 bits only
x << 6 + (encoded_codepoint(2) & %00111111)
x << 6 + (encoded_codepoint(3) & %00111111)
x << 6 + (encoded_codepoint(4) & %00111111)
EndSelect
 
ProcedureReturn x
EndProcedure
 
;helper procedure to format output for this example
Procedure.s formatOutput(c$, c, Array encoded_utf.a(1), dcp) ;character, codepooint, UTf8 encoding, decoded codepoint
Protected o$, i, encoding$
 
o$ = " " + LSet(c$, 8) + LSet("U+" + RSet(Hex(c), 5, "0"), 10)
For i = 1 To encoded_utf(0)
encoding$ + RSet(Hex(encoded_utf(i)), 2, "0") + " "
Next
o$ + " " + LSet(encoding$, 11, " ") + " " + RSet(Hex(dcp), 5, "0")
 
ProcedureReturn o$
EndProcedure
 
DataSection
;unicode code points in hex
unicode_codepoints:
Data.i 5, $41, $F6, $416, $20AC, $1D11E
;The names for these codepoints are: latin capital letter a; latin small letter o With diaeresis
;cyrillic capital letter zhe; euro sign; musical symbol g clef.
EndDataSection
 
;read initial unicode codepoint values
Restore unicode_codepoints
Read num_codepoints
num_codepoints - 1
 
Dim codepoint(num_codepoints)
For i = 0 To num_codepoints
Read codepoint(i)
Next
 
;This array is used for input and output from the UTF8 encode and decode procedures. After encoding its elements
;hold the byte count of the encoding followed by the respective bytes. For decoding element zero is not used and
;elements 1 To 4 holds the bytes to be decoded.
Dim encoded_codepoint.a(#UTF8_codePointMaxByteCount)
If OpenConsole("", #PB_UTF8)
PrintN(LSet("", 11) + LSet("Unicode", 12) + LSet("UTF-8",14) + LSet("Decoded",12))
PrintN(LSet("Character", 11) + LSet("Code Point", 12) + LSet("Encoding",14) + LSet("Code Point",12))
PrintN(LSet("---------", 11) + LSet("----------", 12) + LSet("-----------",14) + LSet("-----------",12))
 
For i = 0 To num_codepoints
UTF8_encode(codepoint(i), encoded_codepoint())
dcp = UTF8_decode(encoded_codepoint()) ;Decoded UTF-8 encoding should match original codepoint that was encoded.
PrintN(formatOutput(Chr(codepoint(i)), codepoint(i), encoded_codepoint(), dcp))
Next
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
CloseConsole()
EndIf

Sample output:

           Unicode     UTF-8         Decoded
Character  Code Point  Encoding      Code Point
---------  ----------  -----------   -----------
   A       U+00041     41            00041
   ΓΆ       U+000F6     C3 B6         000F6
   ?       U+00416     D0 96         00416
   ?       U+020AC     E2 82 AC      800AC
   ?       U+1D11E     F0 9D 84 9E   1D11E

Python[edit]

 
#!/usr/bin/env python3
from unicodedata import name
 
 
def unicode_code(ch):
return 'U+{:04x}'.format(ord(ch))
 
 
def utf8hex(ch):
return " ".join([hex(c)[2:] for c in ch.encode('utf8')]).upper()
 
 
if __name__ == "__main__":
print('{:<11} {:<36} {:<15} {:<15}'.format('Character', 'Name', 'Unicode', 'UTF-8 encoding (hex)'))
chars = ['A', 'ΓΆ', 'Π–', '€', 'π„ž']
for char in chars:
print('{:<11} {:<36} {:<15} {:<15}'.format(char, name(char), unicode_code(char), utf8hex(char)))
Output:
Character   Name                                 Unicode         UTF-8 encoding (hex)
A           LATIN CAPITAL LETTER A               U+0041          41             
ΓΆ           LATIN SMALL LETTER O WITH DIAERESIS  U+00f6          C3 B6          
Π–           CYRILLIC CAPITAL LETTER ZHE          U+0416          D0 96          
€           EURO SIGN                            U+20ac          E2 82 AC       
π„ž           MUSICAL SYMBOL G CLEF                U+1d11e         F0 9D 84 9E

Racket[edit]

#lang racket
 
(define char-map
'((LATIN-CAPITAL-LETTER-A . #\U0041)
(LATIN-SMALL-LETTER-O-WITH-DIAERESIS . #\U00F6)
(CYRILLIC-CAPITAL-LETTER-ZHE . #\U0416)
(EURO-SIGN . #\U20AC)
(MUSICAL-SYMBOL-G-CLEF . #\U1D11E)))
 
(for ((name.char (in-list char-map)))
(define name (car name.char))
(define chr (cdr name.char))
(let ((bites (bytes->list (string->bytes/utf-8 (list->string (list chr))))))
(printf "~s\t~a\t~a\t~a\t~a~%" chr chr
(map (curryr number->string 16) bites)
(bytes->string/utf-8 (list->bytes bites))
name)))
Output:
#\A	A	(41)	A	LATIN-CAPITAL-LETTER-A
#\ΓΆ	ΓΆ	(c3 b6)	ΓΆ	LATIN-SMALL-LETTER-O-WITH-DIAERESIS
#\Π–	Π–	(d0 96)	Π–	CYRILLIC-CAPITAL-LETTER-ZHE
#\€	€	(e2 82 ac)	€	EURO-SIGN
#\π„ž	π„ž	(f0 9d 84 9e)	π„ž	MUSICAL-SYMBOL-G-CLEF

Scala[edit]

Imperative solution[edit]

object UTF8EncodeAndDecode extends App {
 
val codePoints = Seq(0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E)
 
def utf8Encode(codepoint: Int): Array[Byte] =
new String(Array[Int](codepoint), 0, 1).getBytes(StandardCharsets.UTF_8)
 
def utf8Decode(bytes: Array[Byte]): Int =
new String(bytes, StandardCharsets.UTF_8).codePointAt(0)
 
println("Char Name Unicode UTF-8 Decoded")
for (codePoint <- codePoints) {
val w = if (Character.isBmpCodePoint(codePoint)) 4 else 5 // Compute spacing
val bytes = utf8Encode(codePoint)
 
def leftAlignedHex = f"U+${codePoint}%04X"
 
val s = new StringBuilder()
bytes.foreach(byte => s ++= "%02X ".format(byte))
 
printf(s"%-${w}c %-36s %-7s  %-${16 - w}s%c%n",
codePoint, Character.getName(codePoint), leftAlignedHex, s, utf8Decode(bytes))
}

Functional solution[edit]

import java.nio.charset.StandardCharsets
 
object UTF8EncodeAndDecode extends App {
 
val codePoints = Seq(0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E)
 
def utf8Encode(codepoint: Int): Array[Byte] =
new String(Array[Int](codepoint), 0, 1).getBytes(StandardCharsets.UTF_8)
 
def utf8Decode(bytes: Array[Byte]): Int =
new String(bytes, StandardCharsets.UTF_8).codePointAt(0)
 
println("Char Name Unicode UTF-8 Decoded")
codePoints.foreach{ codePoint =>
val w = if (Character.isBmpCodePoint(codePoint)) 4 else 5 // Compute spacing
val bytes = utf8Encode(codePoint)
 
def leftAlignedHex: String = f"U+${codePoint}%04X"
 
def utf: String = bytes.foldLeft("")(_ + "%02X ".format(_))
 
printf(s"%-${w}c %-36s %-7s  %-${16 - w}s%c%n",
codePoint, Character.getName(codePoint), leftAlignedHex, utf, utf8Decode(bytes)) }
 
println(s"\nSuccessfully completed without errors. [total ${scala.compat.Platform.currentTime - executionStart} ms]")
}

Composable and testable solution[edit]

package example
 
object UTF8EncodeAndDecode extends TheMeat with App {
val codePoints = Seq(0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E)
 
println("Char Name Unicode UTF-8 Decoded")
codePoints.foreach { codepoint => print(composeString(codepoint)) }
 
println(s"\nSuccessfully completed without errors. [total ${scala.compat.Platform.currentTime - executionStart} ms]")
}
 
trait TheMeat {
import java.nio.charset.StandardCharsets
 
def composeString(codePoint: Int): String = {
val w = if (Character.isBmpCodePoint(codePoint)) 4 else 5 // Compute spacing
val bytes = utf8Encode(codePoint)
 
def leftAlignedHex: String = f"U+${codePoint}%04X"
 
def utf: String = bytes.foldLeft("")(_ + "%02X ".format(_))
 
s"%-${w}c %-36s %-7s  %-${16 - w}s%c%n"
.format(codePoint, Character.getName(codePoint), leftAlignedHex, utf, utf8Decode(bytes))
}
 
def utf8Encode(codepoint: Int): Array[Byte] =
new String(Array[Int](codepoint), 0, 1).getBytes(StandardCharsets.UTF_8)
 
def utf8Decode(bytes: Array[Byte]): Int =
new String(bytes, StandardCharsets.UTF_8).codePointAt(0)
 
}
 

Seed7[edit]

$ include "seed7_05.s7i";
include "unicode.s7i";
include "console.s7i";
include "bytedata.s7i";
 
const proc: main is func
local
var char: ch is ' ';
var string: utf8 is "";
begin
OUT := STD_CONSOLE;
writeln("Character Unicode UTF-8 encoding (hex) Decoded");
writeln("-------------------------------------------------");
for ch range "AΓΆΠ–β‚¬π„ž" do
utf8 := striToUtf8(str(ch));
writeln(ch rpad 11 <& "U+" <& ord(ch) radix 16 lpad0 4 rpad 7 <&
hex(utf8) rpad 22 <& utf8ToStri(utf8));
end for;
end func;
Output:
Character  Unicode  UTF-8 encoding (hex)  Decoded
-------------------------------------------------
A          U+0041   41                    A
ΓΆ          U+00f6   c3b6                  ΓΆ
Π–          U+0416   d096                  Π–
€          U+20ac   e282ac                €
π„ž          U+1d11e  f09d849e              π„ž

Sidef[edit]

func utf8_encoder(Number code) {
code.chr.encode('UTF-8').bytes.map{.chr}
}
 
func utf8_decoder(Array bytes) {
bytes.map{.ord}.decode('UTF-8')
}
 
for n in ([0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E]) {
var encoded = utf8_encoder(n)
var decoded = utf8_decoder(encoded)
assert_eq(n, decoded.ord)
say "#{decoded} -> #{encoded}"
}
Output:
A -> ["A"]
ΓΆ -> ["\xC3", "\xB6"]
Π– -> ["\xD0", "\x96"]
€ -> ["\xE2", "\x82", "\xAC"]
π„ž -> ["\xF0", "\x9D", "\x84", "\x9E"]

Swift[edit]

In Swift there's a difference between UnicodeScalar, which is a single unicode code point, and Character which may consist out of multiple UnicodeScalars, usually because of combining characters.

import Foundation
 
func encode(_ scalar: UnicodeScalar) -> Data {
return Data(String(scalar).utf8)
}
 
func decode(_ data: Data) -> UnicodeScalar? {
guard let string = String(data: data, encoding: .utf8) else {
assertionFailure("Failed to convert data to a valid String")
return nil
}
assert(string.unicodeScalars.count == 1, "Data should contain one scalar!")
return string.unicodeScalars.first
}
 
for scalar in "AΓΆΠ–β‚¬π„ž".unicodeScalars {
let bytes = encode(scalar)
let formattedBytes = bytes.map({ String($0, radix: 16)}).joined(separator: " ")
let decoded = decode(bytes)!
print("character: \(decoded), code point: U+\(String(scalar.value, radix: 16)), \tutf-8: \(formattedBytes)")
}
 
Output:
character: A, code point: U+41, 	utf-8: 41
character: ΓΆ, code point: U+f6, 	utf-8: c3 b6
character: Π–, code point: U+416, 	utf-8: d0 96
character: €, code point: U+20ac, 	utf-8: e2 82 ac
character: π„ž, code point: U+1d11e, 	utf-8: f0 9d 84 9e

Tcl[edit]

Note: Tcl can handle Unicodes only up to U+FFFD, i.e. the Basic Multilingual Plane (BMP, 16 bits wide). Therefore, the fifth test fails as expected.

proc encoder int {
set u [format %c $int]
set bytes {}
foreach byte [split [encoding convertto utf-8 $u] ""] {
lappend bytes [format %02X [scan $byte %c]]
}
return $bytes
}
proc decoder bytes {
set str {}
foreach byte $bytes {
append str [format %c [scan $byte %x]]
}
return [encoding convertfrom utf-8 $str]
}
foreach test {0x0041 0x00f6 0x0416 0x20ac 0x1d11e} {
set res $test
lappend res [encoder $test] -> [decoder [encoder $test]]
puts $res
}
0x0041 41 -> A
0x00f6 {C3 B6} -> ΓΆ
0x0416 {D0 96} -> Π–
0x20ac {E2 82 AC} -> €
0x1d11e {EF BF BD} -> οΏ½

Alternative Implementation[edit]

While perhaps not as readable as the above, this version handles beyond-BMP codepoints by manually composing the utf-8 byte sequences and emitting raw bytes to the console. encoding convertto utf-8 command still does the heavy lifting where it can.

proc utf8 {codepoint} {
scan $codepoint %llx cp
if {$cp < 0x10000} {
set str [subst \\u$codepoint] ;# substitute per Tcl backslash rule
set bytes [encoding convertto utf-8 $str] ;# encode
} else { ;# codepoints beyond the BMP need manual approach
set bits [format %021b $cp] ;# format as binary string
set unibits 11110[string range $bits 0 2];# insert extra bits for utf-8 4-byte encoding
append unibits 10[string range $bits 3 8]
append unibits 10[string range $bits 9 14]
append unibits 10[string range $bits 15 20]
set bytes [binary format B* $unibits] ;# turn into a sequence of bytes
}
return $bytes
}
 
proc hexchars {s} {
binary scan $s H* hex
regsub -all .. $hex {\0 }
}
 
# for the test, we assume the tty is in utf-8 mode and can handle beyond-BMP chars
# so set output mode to binary so we can write raw bytes!
chan configure stdout -encoding binary
foreach codepoint { 41 F6 416 20AC 1D11E } {
set utf8 [utf8 $codepoint]
puts "[format U+%04s $codepoint]\t$utf8\t[hexchars $utf8]"
}
Output:
U+0041  A       41

U+00F6 ΓΆ c3 b6 U+0416 Π– d0 96 U+20AC € e2 82 ac U+1D11E π„ž f0 9d 84 9e

VBA[edit]

Private Function unicode_2_utf8(x As Long) As Byte()
Dim y() As Byte
Dim r As Long
Select Case x
Case 0 To &H7F
ReDim y(0)
y(0) = x
Case &H80 To &H7FF
ReDim y(1)
y(0) = 192 + x \ 64
y(1) = 128 + x Mod 64
Case &H800 To &H7FFF
ReDim y(2)
y(2) = 128 + x Mod 64
r = x \ 64
y(1) = 128 + r Mod 64
y(0) = 224 + r \ 64
Case 32768 To 65535 '&H8000 To &HFFFF equals in VBA as -32768 to -1
ReDim y(2)
y(2) = 128 + x Mod 64
r = x \ 64
y(1) = 128 + r Mod 64
y(0) = 224 + r \ 64
Case &H10000 To &H10FFFF
ReDim y(3)
y(3) = 128 + x Mod 64
r = x \ 64
y(2) = 128 + r Mod 64
r = r \ 64
y(1) = 128 + r Mod 64
y(0) = 240 + r \ 64
Case Else
MsgBox "what else?" & x & " " & Hex(x)
End Select
unicode_2_utf8 = y
End Function
Private Function utf8_2_unicode(x() As Byte) As Long
Dim first As Long, second As Long, third As Long, fourth As Long
Dim total As Long
Select Case UBound(x) - LBound(x)
Case 0 'one byte
If x(0) < 128 Then
total = x(0)
Else
MsgBox "highest bit set error"
End If
Case 1 'two bytes and assume first byte is leading byte
If x(0) \ 32 = 6 Then
first = x(0) Mod 32
If x(1) \ 64 = 2 Then
second = x(1) Mod 64
Else
MsgBox "mask error"
End If
Else
MsgBox "leading byte error"
End If
total = 64 * first + second
Case 2 'three bytes and assume first byte is leading byte
If x(0) \ 16 = 14 Then
first = x(0) Mod 16
If x(1) \ 64 = 2 Then
second = x(1) Mod 64
If x(2) \ 64 = 2 Then
third = x(2) Mod 64
Else
MsgBox "mask error last byte"
End If
Else
MsgBox "mask error middle byte"
End If
Else
MsgBox "leading byte error"
End If
total = 4096 * first + 64 * second + third
Case 3 'four bytes and assume first byte is leading byte
If x(0) \ 8 = 30 Then
first = x(0) Mod 8
If x(1) \ 64 = 2 Then
second = x(1) Mod 64
If x(2) \ 64 = 2 Then
third = x(2) Mod 64
If x(3) \ 64 = 2 Then
fourth = x(3) Mod 64
Else
MsgBox "mask error last byte"
End If
Else
MsgBox "mask error third byte"
End If
Else
MsgBox "mask error second byte"
End If
Else
MsgBox "mask error leading byte"
End If
total = CLng(262144 * first + 4096 * second + 64 * third + fourth)
Case Else
MsgBox "more bytes than expected"
End Select
utf8_2_unicode = total
End Function
Public Sub program()
Dim cp As Variant
Dim r() As Byte, s As String
cp = [{65, 246, 1046, 8364, 119070}] '[{&H0041,&H00F6,&H0416,&H20AC,&H1D11E}]
Debug.Print "ch unicode UTF-8 encoded decoded"
For Each cpi In cp
r = unicode_2_utf8(CLng(cpi))
On Error Resume Next
s = CStr(Hex(cpi))
Debug.Print ChrW(cpi); String$(10 - Len(s), " "); s,
If Err.Number = 5 Then Debug.Print "?"; String$(10 - Len(s), " "); s,
s = ""
For Each yz In r
s = s & CStr(Hex(yz)) & " "
Next yz
Debug.Print String$(13 - Len(s), " "); s;
s = CStr(Hex(utf8_2_unicode(r)))
Debug.Print String$(8 - Len(s), " "); s
Next cpi
End Sub
Output:
ch  unicode  UTF-8 encoded  decoded

A 41 41 41 ΓΆ F6 C3 B6 F6 ? 416 D0 96 416 € 20AC E2 82 AC 20AC ? 1D11E F0 9D 84 9E 1D11E

zkl[edit]

println("Char  Unicode  UTF-8");
foreach utf,unicode_int in (T( T("\U41;",0x41), T("\Uf6;",0xf6),
T("\U416;",0x416), T("\U20AC;",0x20ac), T("\U1D11E;",0x1d11e))){
utf_int:=utf.reduce(fcn(s,c){ 0x100*s + c.toAsc() },0);
char :=unicode_int.toString(-8); // Unicode int to UTF-8 string
// UTF-8 bytes to UTF-8 string:
char2:=Data(Void,utf_int.toBigEndian(utf_int.len())).text;
 
println("%s %s %9s  %x".fmt(char,char2,"U+%x".fmt(unicode_int),utf_int));
}

Int.len() --> number of bytes in int. This could be hard coded because UTF-8 has a max of 6 bytes and (0x41).toBigEndian(6) --> 0x41,0,0,0,0,0 which is a zero terminated string ("A");

Output:
Char  Unicode  UTF-8
A A      U+41  41
ΓΆ ΓΆ      U+f6  c3b6
Π– Π–     U+416  d096
€ €    U+20ac  e282ac
π„ž π„ž   U+1d11e  f09d849e