True color code

Question

True color (24-bit) at Wikipedia is described in pertinent part as

24 bits almost always uses 8 bits of each of R, G, B. As of 2018 24-bit color depth is used by virtually every computer and phone display and the vast majority of image storage formats. Almost all cases where there are 32 bits per pixel mean that 24 are used for the color, and the remaining 8 are the alpha channel or unused.

2²⁴ gives 16,777,216 color variations. The human eye can discriminate up to ten million colors^[10] and since the gamut of a display is smaller than the range of human vision, this means this should cover that range with more detail than can be perceived. ...

...

Macintosh systems refer to 24-bit color as "millions of colors". The term "True color" is sometime used to mean what this article is calling "Direct color".^[13] It is also often used to refer to all color depths greater or equal to 24.

All 16,777,216 colors

Task

Write a program which generates and returns all 16,777,216 color variations within an array as strings in the CSS rgb() function

5.1. The RGB functions: rgb() and rgba()

The rgb() function defines an RGB color by specifying the red, green, and blue channels directly. Its syntax is:

rgb() = rgb( <percentage>{3} [ / <alpha-value> ]? ) |
        rgb( <number>{3} [ / <alpha-value> ]? )
<alpha-value> = <number> | <percentage>

The first three arguments specify the red, green, and blue channels of the color, respectively. 0% represents the minimum value for that color channel in the sRGB gamut, and 100% represents the maximum value. A <number> is equivalent to a <percentage>, but with a different range: 0 again represents the minimum value for the color channel, but 255 represents the maximum. These values come from the fact that many graphics engines store the color channels internally as a single byte, which can hold integers between 0 and 255. Implementations should honor the precision of the channel as authored or calculated wherever possible. If this is not possible, the channel should be rounded to the closest value at the highest precision used, rounding up if two values are equally close.

The final argument, the <alpha-value>, specifies the alpha of the color. If given as a <number>, the useful range of the value is 0 (representing a fully transparent color) to 1 (representing a fully opaque color). If given as a , 0% represents a fully transparent color, while 100% represents a fully opaque color. If omitted, it defaults to 100%.

Values outside these ranges are not invalid, but are clamped to the ranges defined here at computed-value time.

For legacy reasons, rgb() also supports an alternate syntax that separates all of its arguments with commas:

rgb() = rgb( <percentage>#{3} , <alpha-value>? ) |
        rgb( <number>#{3} , <alpha-value>? )

Also for legacy reasons, an rgba() function also exists, with an identical grammar and behavior to rgb().

or RGB hexadecimal notation #RRGGBB format

5.2. The RGB hexadecimal notations: #RRGGBB

The CSS hex color notation allows a color to be specified by giving the channels as hexadecimal numbers, which is similar to how colors are often written directly in computer code. It’s also shorter than writing the same color out in rgb() notation.

The syntax of a <hex-color> is a <hash-token> token whose value consists of 3, 4, 6, or 8 hexadecimal digits. In other words, a hex color is written as a hash character, "#", followed by some number of digits 0-9 or letters a-f (the case of the letters doesn’t matter - #00ff00 is identical to #00FF00).

The number of hex digits given determines how to decode the hex notation into an RGB color:

6 digits

The first pair of digits, interpreted as a hexadecimal number, specifies the red channel of the color, where 00 represents the minimum value and ff (255 in decimal) represents the maximum. The next pair of digits, interpreted in the same way, specifies the green channel, and the last pair specifies the blue. The alpha channel of the color is fully opaque.

EXAMPLE 2
In other words, #00ff00 represents the same color as rgb(0 255 0) (a lime green).

See Editor's Draft of CSS Color Module Level 4

Examples

CSS rgb() function (space character can be substituted for comma character, e.g., rgb(0 255 0))

// `rgb()` `<percentage>` as strings in resulting array
['rgb(0%,0%,0%)', ...,'rgb(0%,255%,0)', ...'rgb(255,255,255)']

// `rgb()` `<number>` as strings in resulting array
['rgb(0,0,0)', ...,'rgb(0,255,0)', ...'rgb(255,255,255)']

CSS RGB hexadecimal notation RRGGBB

// RGB hexadecimal notation as strings in resulting array
['#000000', ...,'#00ff00', ...'#ffffff']

Winning criteria

Least bytes used to write the program.

Answer 1

R, 25 bytes

sprintf("#%06X",1:2^24-1)

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Answer 2

Python 2, 77 40 39 37 bytes

print['#%06X'%c for c in range(8**8)]

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_{-1 byte thanks to Digital Trauma}

_{-2 bytes thanks to dylnan}

Answer 3

PowerShell, 28 26 bytes

1..16mb|%{"#{0:x6}"-f--$_}

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Loops from 1 to 16mb (16777216). Each iteration, we use the -format operator acting on the current number pre-decremented --$_ against the string "#{0:x6}". Here, we're specifying hex values, padded to 6 digits, with a hash # in front. On TIO, limited to 60 seconds / 128KiB of output. Change the 1 to (16mb-5) to see how it ends.

Answer 4

JavaScript (ES7), 65 62 61 bytes

Saved 3 4 bytes thanks to @tsh

Returns an array of #RRGGBB strings.

_=>[...Array(n=8**8)].map(_=>'#'+(n++).toString(16).slice(1))

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Answer 5

Common Lisp, 42 bytes

(dotimes(i 16777216)(format t"#~6,'0x "i))

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Answer 6

Japt, 14 bytes

Outputs as #rrggbb.

G²³ÇsG ùT6 i'#

Try it (Limited to the first 4096 elements)

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Explanation

G                  :16
 ²                 :Squared
  ³                :Cubed
   Ç               :Map the range [0,result)
    sG             :  Convert to base-16 string
       ù           :  Left pad
        T          :   With 0
         6         :   To length 6
           i'#     :  Prepend "#"

Answer 7

Haskell, 41 bytes

l="ABCDEF"
mapM id$"#":(['0'..'9']++l<$l)

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Answer 8

05AB1E, 15 14 10 bytes

15Ýh6ãJ'#ì

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Explanation:

15Ý           # Create a list in the range [0, 15]
   h          # Convert each to a hexadecimal value
    6ã        # Create each possible sextuple combination of the list
      J       # Join them together to a single string
       '#ì    # And prepend a "#" before each of them

Answer 9

Batch, 87 bytes

@set s= in (0,1,255)do @
@for /l %%r%s%for /l %%g%s%for /l %%b%s%echo rgb(%%r,%%g,%%b)

Outputs in CSS format. The variable substitution happens before the for statement is parsed so the the actual code is as follows:

@for /l %%r in (0,1,255)do @for /l %%g in (0,1,255)do @for /l %%b in (0,1,255)do @echo rgb(%%r,%%g,%%b)

Answer 10

C# (Visual C# Interactive Compiler), 47 bytes

Enumerable.Range(0,1<<24).Select(q=>$"#{q:X6}")

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Answer 11

C# (.NET Core), 75 bytes

()=>{int i=1<<24;var a=new string[i];for(;i-->0;)a[i]=$"#{i:X6}";return a;}

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Port of JAVA 10 version with C# interpolated string format

Answer 12

K (oK), 19 bytes

Solution:

$(3#256)\'!16777216

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Explanation:

Dump out rgb strings. Convert each number between 0 and 16777216 to base 256, then convert to strings...

$(3#256)\'!16777216 / the solution
          !16777216 / range 0..16777215
 (     )\'          / split each both
  3#256             / 256 256 256
$                   / string

Answer 13

MATL, 17 15 bytes

10W:q'#%06X,'YD

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The TIO version displays the first 2^10 only as not to time out. I included the final iteration in the footer to show that it indeed terminates at #FFFFFF. Saved one byte by changing to fprintf instead of manually assembling the string. Outputs a comma-separated list.

Explanation

24W:q            % Range from 0 to 2^24-1
     '#%06X,'    % fprintf format spec (# followed by hexadecimal, zero-padded, fixed-width, followed by newline)
             YD  % Call fprintf. Internally loops over range.

Answer 14

APL (Dyalog Unicode), 47 43 20 bytes

'#',(⎕D,⎕A)[↑,⍳6⍴16]

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Given enough time/memory, this anonymous function will output all \$2^{24}-1\$ color codes. To see this, you can swap the 6⍴ for a 4⍴ in the code, and you'll see it output every code with up to 4 digits.

Thanks to @Dzaima and @ngn for the 23 bytes.

Uses ⎕IO←0.

How:

'#',(⎕D,⎕A)[↑,⍳6⍴16] ⍝ Main function
               ⍳6⍴16  ⍝ Generate every possible 6 digit hex number in a matrix format
              ,       ⍝ Ravel the matrix (from a 16x16x16x16x16x16 matrix to a 16^6x2 list)
             ↑        ⍝ Mix; (turns the list into a 16^6x2 matrix)
    (⎕D,⎕A)[       ] ⍝ Use that matrix to index the vector of the digits 0-9 concatenated with the alphabet.
'#',                  ⍝ Then prepend a '#' to each.

Answer 15

Ruby, 31 bytes

$><<("#%06x\n"*d=2**24)%[*0..d]

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Answer 16

V, 25 bytes

8É00lrx16777215ñÄ<C-a>ñ0<C-v>Gls#

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Explanation

8É0                                " insert 8 zeroes
   0l                              " move cursor to the second character
     rx                            " replace by x
       16777215ñ      ñ            " 16777215 times do ..
                Ä                  " .. duplicate line
                 <C-a>             " .. increment (leading 0x makes sure it uses hexadecimals)
                       0<C-v>      " move cursor to beginning of line and start selection
                             Gl    " select the column with 0x
                               s#  " replace by #

Answer 17

Batch, 69 + 4 = 73

g.cmd, 69

for /L %%A in (0,1,16777215)do cmd/kexit %%A&set #%%A=#!=exitcode:~2!

Saves the hexadecimal value with form #RRGGBB into an 'Array'.

g.cmd is to be called using cmd /V/Q/K g.cmd. This is where the + 4 comes from, /V/Q, counting as 4 additional characters compared to just cmd /K g.cmd. This sets up an environment that has the 'Array' in memory. It also takes forever to run, so use very low values to try or break execution using Ctrl+C

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Breakdown

Invokation

• /V enables delayed expansion, but is shorter than setlocal EnableDelayedExpansion, which is why we need the cmd call in the first place
• /Q omits the output and is equivalent to @echo off
• /K lets you execute an expression (In this case g.cmd) and does not exit afterwards, so you can check the 'Array' by using set #

g.cmd

for /L %%A IN (0,1,16777215) DO (
    cmd /k exit %%A
    set #%%A=#!=exitcode:~2!
)

This bit uses a trick documented here to convert a normal number to a hexadecimal, then saves that value into an 'Array'.

---

I've been calling that storing structure an 'Array' but that is not actually right as true Arrays do not exist in Batch. BUT you can name variables so that they have arraylike names, like so:

set elem[1]=First element
set elem[2]=Second one

or, like in this case:

set #1=First element
set #2=Second one

You can still access them via !#%position%!

Answer 18

Groovy, 53 bytes

c={a=[];(1<<24).times{a.add "".format("#%06x",it)};a}

Function definition. c() returns an ArrayList (I assume that's fine, even through the question asks for an array).

Ungolfed, with implicit types:

ArrayList<String> c = {
    ArrayList<String> a = []
    (1 << 24).times { 
        a.add("".format("#%06x", it)) // add the hex-formatted number to the list.
    }
    return a
}

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Answer 19

Java 10, 87 84 bytes

v->{int i=1<<24;var r=new String[i];for(;i-->0;)r[i]="".format("#%06X",i);return r;}

-3 bytes thanks to @archangel.mjj.

Try it online (limited to the first 4,096 items).

Explanation:

v->{                       // Method with empty unused parameter & String-array return-type
  int i=1<<24;             //  Integer `i`, starting at 16,777,216
  var r=new String[i];     //  Result String-array of that size
  for(;i-->0;)             //  Loop `i` in the range (16777216, 0]
    r[i]=                  //   Set the `i`'th item in the array to:
      "".format("#%06X",i);//   `i` converted to a hexadecimal value (of size 6)
  return r;}               //  Return the result-array

Answer 20

PHP, 68 62 bytes

This is supposed to be placed inside a file, the array is returned in the end, to be usable.

<?foreach(range(0,1<<24)as$i)$a[]=sprintf('#%06x',$i);return$a;

To have access to the array, simply give the result of the include (e.g.: $a = include 'xyz.php';) to a variable.

---

Thanks to @manatwork for saving me 6 bytes and fix a goof.

Answer 21

MATL, 11 bytes

'#'5Y26Z^Yc

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Explanation

'#'   % Push this character
5Y2   % Push '01234567890ABCDEF'
6     % Push 6
Z^    % Cartesian power. Gives a (16^6)×6 char matrix
Yc    % String concatenation. '#' is implicitly replicated
      % Implicitly display

Answer 22

Bash + jot, 22

jot -w\#%06X $[8**8] 0

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Answer 23

Perl 5, 31 bytes

printf"#%06X
",$_ for 0..8**8-1

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Answer 24

Lua, 47 45 bytes

for i=1,8^8 do s='#%06X'print(s:format(i))end

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Answer 25

T-SQL, 122 117 bytes

Returns a 16,777,216-row table of #RRGGBB strings. The line break is for readability only:

WITH t AS(SELECT 0n UNION ALL SELECT n+1FROM t WHERE n<16777215)
SELECT'#'+FORMAT(n,'X6')FROM t option(maxrecursion 0)

Uses a recursive CTE for a number table from 0 to 2^24-1, then uses the built-in FORMAT command (available in SQL 2012 or later) to turn it into a 6-digit hex string. Attach the # to the front, and we're done.

Edit 1: Removed POWER() function, the number was shorter :P

Answer 26

Jelly, 12 bytes

⁴ṖṃØHœċ6ṭ€”#

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Answer 27

Jelly, 8 bytes

ØHṗ6”#;Ɱ

Try it online! (note: uses 2 rather than 6 as 6 times out on TIO)

Function submission (because Jelly full programs will, by default, print lists of strings with no delimiters between them, making it hard to see the boundaries). The TIO link contains a wrapper to print a list of strings using newlines to separate them.

Explanation

ØHṗ6”#;Ɱ
ØH         All hex digits (“0123456789ABCDEF”)
  ṗ6       Find all strings of 6 of them (order relevant, repeats allowed)
    ”#;    Prepend “#”
       Ɱ     to each of the resulting strings

Answer 28

PHP, 43 bytes

<?php for(;$i<1<<24;printf("#%06X ",$i++));

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Answer 29

Scala, 40 bytes

(1 to 1<<24).map(x=>println(f"#$x%06x"))

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Answer 30

Perl 6, 26 bytes

{map *.fmt("#%06X"),^8**8}

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Uses the same format as everyone else. Times out on TIO.

Or, in rgb format:

31 bytes

{map {"rgb($_)"},[X] ^256 xx 3}

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