When will Brexit happen?

Question

Well, Brexit happened. And Sky News, being the geniuses they are, have decided to create a countdown on the side of a bus.

Your job is to do something similar. The UK leaves the the EU on 31st of March 2019 and you have to create a digital countdown for this that changes every second (with a 0.05 second deviation allowed).

Input

Your program should take absolutely no input. It is banned!

Output

It should output the time until Brexit in the format ddd:hh:mm:ss. Leading and trailing newlines are allowed but the display should stay in the same place each time. It should look as though it is actually decreasing in place. As pointed out by @AnthonyPham this doesn't mean printing enough newlines to "clear" the screen, this means that you must actually clear the screen.

An output like this isn't allowed:

100:20:10:05
100:20:10:04

Neither is this

100:20:10:05
*A thousand newlines*
100:20:10:04

as they're on more than one line.

You don't have to worry about after Brexit. Your program only has to work up to 31/3/2019

Rules

• Standard loopholes are disallowed
• This is code-golf so shortest code in bytes wins.
• Error messages (although I can't think how) are disallowed
• The code should be able to be run in 2 years time (when the UK leaves the EU) and should display the actual time and not start from 730 again (see below)

Countdown rule

The countdown should not be hard-coded and should be able to run at any time before Brexit finishes and still produce the correct result. When a new day is begun the hour should follow the below format

712:00:00:01
712:00:00:00
711:23:59:59

Let me say again, the date Brexit finishes is 31/3/2019 at midnight for convenience (31:3:19 00:00:00 or 31:3:2019 00:00:00 or any other format you want)

NB: I think I have everything but I didn't post this in the Sandbox, otherwise the timing could have been off. Feel free to post any suggestions for improvements because it isn't perfect.

Answer 1

JavaScript, 134 129 113 bytes

setInterval("d=-new Date;document.body.innerHTML=`<pre>${d/864e5+17986|0}:`+new Date(d).toJSON().slice(11,19)",1)

Edit: Saved 2 bytes thanks to @Shaggy. Saved 11 bytes thanks to @l4m2.

Answer 2

PowerShell, 70 63 55 53 Bytes

Excluded double quotes, easy -2 thanks to @Joey

for(){cls;(date 31Mar19)-(date)|% T* ddd\:hh\:mm\:ss}

Running this with sleep adds 8 bytes, but the input is mostly invisible if it is run without them, version (63 bytes) with sleep:

for(){cls;(date 31/3/19)-(date)|% T* ddd\:hh\:mm\:ss;sleep 1}

for() is an infinite loop, and within that loop..

cls to clear the screen,

get 31/3/19 as a DateTime object, and - the current date from it, to give the time remaining, then .ToString() (|% T*) that with the correct format.

this will display negative time after brexit.

Answer 3

Python 3.6, 146 bytes

from datetime import*
x=datetime
while 1:d=x(2019,3,31)-x.now();s=d.seconds;a=s%3600;print(end=f"\r{d.days:03}:{s//3600:02}:{a//60:02}:{s%60:02}")

Answer 4

Excel VBA, 91 84 82 bytes

^{Saved 7 bytes thanks to JoeMalpass pointing out that Excel sees dates as numbers.
Saved 2 bytes thanks to JoeMalpass}

Sub b()
Do
t=CDec(43555-Now)
Cells(1,1)=Int(t) &Format(t,":hh:mm:ss")
Loop
End Sub

Output is to cell A1 in the active Excel sheet.

Answer 5

C#, 173 172 156 150 127 bytes

using System;class P{static void Main(){for(;;)Console.Write($"\r{new DateTime(2019,3,31)-DateTime.Now:d\\:hh\\:mm\\:ss}  ");}}

Saved 16 bytes thanks to @Bob Saved 6 bytes thanks to @Søren D. Ptæus

Formatted version:

using System;

class P
{
    static void Main()
    {
        for (;;)
            Console.Write($"\r{new DateTime(2019, 3, 31) - DateTime.Now:d\\:hh\\:mm\\:ss}  ");
    }
}

Answer 6

AHK, 145 Bytes

This is not the shortest answer but the result gives a very nice feeling of doom, I think. I originally tried to send the keystrokes Ctrl+A followed by DEL and then whatever the time was but the refresh rate was too slow and it would destroy whatever environment you were in. Instead, then, I went with the GUI. It turned out to take less bytes to completely destroy the window and recreate it than it did to update the control over and over so I went with that. It's a nice effect.

Loop{
s=20190331000000
s-=A_Now,S
d:=t:=20000101000000
t+=s,S
d-=t,D
d*=-1
FormatTime f,%t%,:HH:mm:ss
GUI,Destroy
GUI,Add,Text,,%d%%f%
GUI,Show
}

Answer 7

JavaScript ES5, 320 319 316 305 295 284 bytes

setInterval(function(){a=Math,b=a.floor,c=console,d=Date,e="00",f=new d(2019,2,31),g=a.abs(f-new d)/1e3,h=b(g/86400);g-=86400*h;var i=b(g/3600)%24;g-=3600*i;var j=b(g/60)%60;g-=60*j,c.clear(),c.log((e+h).slice(-3)+":"+(e+i).slice(-2)+":"+(e+j).slice(-2)+":"+(e+a.ceil(g)).slice(-2))})

Thanks to @Fels for referencing Math, @dgrcode for referencing console

Un-golfed

setInterval(function() {

  var math = Math, floor = math.floor, c = console, d = Date;

  var leadings = "00";

  // set our brexit date
  var brexit = new d(2019, 2, 31);

  // get total seconds between brexit and now
  var diff = math.abs(brexit - new d()) / 1000;

  // calculate (and subtract) whole days
  var days = floor(diff / 86400);
  diff -= days * 86400;

  // calculate (and subtract) whole hours
  var hours = floor(diff / 3600) % 24;
  diff -= hours * 3600;

  // calculate (and subtract) whole minutes
  var minutes = floor(diff / 60) % 60;
  diff -= minutes * 60;

  // what's left is seconds

  // clear the console (because OP said it must print in the same place)
  c.clear();

  // log the countdown, add the leadings and slice to get the correct leadings 0's
  c.log((leadings + days).slice(-3) + ":" + (leadings + hours).slice(-2) + ":" + (leadings + minutes).slice(-2) + ":" + (leadings + math.ceil(diff)).slice(-2));

});

Answer 8

PHP, 84 bytes

for(;$c=DateTime;)echo(new$c('@1553990400'))->diff(new$c)->format("\r%a:%H:%I:%S ");

Fairly straightforward. 1553990400 is the timestamp for 31-3-2019 00:00:00 in UTC. It loops infinitely, using DateTime->diff()->format() to output how much time is left. After Brexit has happened, it will start counting up from 0.

Commented / more readable version:

// Infinite loop, assign DateTime (as a string) to $class
for (; $class = DateTime;) {
    echo (new $class('@1553990400')) // Create a new DateTime object for the brexit date/time.
            ->diff(new $class) // Caulculate the difference to the current date/time.
            ->format("\r%a:%H:%I:%S "); // Format it according to the specification, starting with a \r character to move to the start of the line and overwrite the previous output.
}

Answer 9

CJam, 69 62 59 57 bytes

Saved 7 bytes by converting to time format differently

Saved 3 bytes thanks to Martin Ender's suggestions

Saved 2 bytes by using a carriage return instead of backspaces

{15539904e5esm1e3/{60md\}2*24md\]W%{sYTe[}%':*CTe[oDco1}g

Can't be run on TIO for obvious reasons.

It rewrites the display constantly in an infinite loop so the text kind of flashes in and out (at least in my console), although it only actually updates the time once per second.

This 70-byte version only prints once per second:

{15539904e5es:Xm1e3/{60md\}2*24md\]W%{sYTe[}%':*CTe[oDco{esXm1e3<}g1}g

Explanation

{                           e# Begin a while loop
  15539904e5                e#  The timestamp on which Brexit will occur
  es                        e#  The current timestamp
  m                         e#  Subtract
  1e3/                      e#  Integer divide by 1000, converting to seconds from ms
  {                         e#  Run this block twice
   60md                     e#   Divmod by 60
   \                        e#   Swap top elements
  }2*                       e#  (end of block) 
                            e#    This block divmods the timestamp by 60, resulting in 
                            e#    the remaining minutes and seconds. Then the minutes get 
                            e#    divmod-ed by 60, to get hours and minutes remaining
  24md\                     e#  Divmod hours remaining by 24 and swap top elements, to get
                            e#    the hours left and days left.
  ]                         e#  Wrap the entire stack in an array
  W%                        e#  Reverse it since it's currently in the wrong order
  {                         e#  Apply this block to each element of the array
   s                        e#   Cast to string (array of digit characters)
   YTe[                     e#   Pad to length 2 by adding 0s to the left
  }%                        e#  (end of map block)
  ':*                       e#  Join with colons
  CTe[                      e#  Pad to length 12 by adding 0s to the left, dealing with the
                            e#    special case of the day being 3 digits. 
  o                         e#  Pop and print the resulting string, which is the time
  Dco                       e#  Print a carriage return, moving the cursor back to the start
  1                         e#  Push 1
}g                          e# Pop 1, if it's true, repeat (infinite loop)

Answer 10

Python 3.5 (118 Bytes)

import datetime as d,os
d=d.datetime
while 1:os.system("cls");e=str(d(2019,3,31)-d.today());print(e[:3]+':'+e[-15:-7])

Answer 11

C#6, 149 bytes

Thanks to Bob for saving 57 bytes!

using System;class P{static void Main(){DateTime a,x=new DateTime(2019,3,31);while((a=DateTime.Now)<x)Console.Write($"\r{x-a:ddd\\:hh\\:mm\\:ss}");}}

Ungolfed program:

using System;

class P
{
    static void Main()
    {
        DateTime a,
                x = new DateTime(2019, 3, 31);
        while ( (a = DateTime.Now) < x)
            Console.Write($"\r{x-a:ddd\\:hh\\:mm\\:ss}");
    }
}

---

C#, 210 206 159 bytes

Thanks to Bob for saving another 47 bytes!

Thanks to Martin Smith for saving 4 bytes!

using System;class P{static void Main(){DateTime a,x=new DateTime(2019,3,31);while((a=DateTime.Now)<x)Console.Write("\r"+(x-a).ToString(@"ddd\:hh\:mm\:ss"));}}

Ungolfed program:

using System;

class P
{
    static void Main()
    {
        DateTime a,
                x = new DateTime(2019, 3, 31);
        while ( (a = DateTime.Now) < x)
            Console.Write("\r" + (x - a).ToString(@"ddd\:hh\:mm\:ss"));
    }
}

Answer 12

C, 104 bytes

main(x){for(;x=1553990400-time(0);)printf("\n%03d:%02d:%02d:%02d\e[1A",x/86400,x/3600%24,x/60%60,x%60);}

Breakdown

main(x){
    for(;x=1553990400-time(0);)             // Seconds remaining
        printf("\n%03d:%02d:%02d:%02d\e[1A",// Move cursor and print:
            x/86400,                        // Days
            x/3600%24,                      // Hours
            x/60%60,                        // Minutes
            x%60);                          // Seconds
    puts("Now we can stop talking about it forever."); // Wishful thinking
}

Relies on time returning number of seconds since 01/01/1970, which is the case for me (using Clang/GCC on macOS) and should be the case for most UNIX stuff.

Uses bash terminal escape sequences to move the cursor around (<esc>[1A moves the cursor up 1 line). It would be nicer to be able to simply use \r, but printf won't flush until it sees a newline, and flushing it manually takes a lot more.

Probably the most CPU intensive countdown I've ever seen. Runs in a hot loop to make sure it's always as accurate as can be. If run after the deadline, it will produce some pretty weird stuff (negatives everywhere!)

Answer 13

C#, 128 127 Bytes

using System;class P{static void Main(){for(;;)Console.Write($"\r{new DateTime(2019,3,31)-DateTime.Now:ddd\\:hh\\:mm\\:ss}");}}

Ungolfed code:

using System;
class P
{
    static void Main()
    {
        for(;;)
            Console.Write($"\r{new DateTime(2019,3,31)-DateTime.Now:ddd\\:hh\\:mm\\:ss}"); 
    }
}

I would not have figured out the \r trick without help from the other C# answers here.

For anyone looking for further improvement, you can also put the Write() expression inside the for loop. Seems like I should be able to save a byte somehow here, because that saves me the semi-colon for that statement, but it works out to the same number because you can't have a fully empty body:

using System;class P{static void Main(){for(;;Console.Write($"\r{new DateTime(2019,3,31)-DateTime.Now:ddd\\:hh\\:mm\\:ss}"));}}

Answer 14

Ruby (83 bytes)

loop{h=431664-Time.now.to_r/3600;$><<['%02d']*4*?:%[h/24,h%24,h%1*60,h*3600%60]+?\r}

Ungolfed

loop do
  seconds = 1553990400 - Time.now.to_r

  print (["%02d"] * 4).join(':') % [
    seconds / 24 / 60 / 60     ,
    seconds      / 60 / 60 % 24,
    seconds           / 60 % 60,
    seconds                % 60,
  ] + "\r"
end

Basically one of the Python submissions, with some improvements. We just emit an "\r" to go beginning of the string before re-rendering. And for the string format of "%03d:%02d:%02d:%02d", we really don't care about the width on the first specifier… so we can just do "%02d"*4, and emit a backspace and a space to clear the extra unnecessary colon.

Also, I found a two-character shorter print: $><<. $> is a shorthand global for $defout, which is the output stream for print and printf and defaults to STDOUT. IO#<< writes the right hand side of it to the stream. How is that two characters shorter? Well, I can now omit the space that led before the parenthesis wrapping the format string.

At this point I genuinely think there is no possible way to shorten this program further in Ruby.

Edit: I was wrong. Instead of the first Time.new(2019,3,31), we can just use the raw UNIX time: 1553990400.

Edit 2: I've tried playing around with factoring out minutes, and dividing the UNIX timestamp by that constant, but it doesn't actually wind up saving any bytes. :(

Edit 3: Turns out caching h=3600 actually hurt me by two bytes. Whoops.

Edit 4: Saved 3 bytes thanks to @EricDuminill. He used floats, but rationals work without loss of precision!

Edit 5: Array#* as an alias for Array#join, with the Ruby ?-syntax for individual characters!

Answer 15

JavaScript+HTML, 136+7=143 bytes

setInterval("d=1553990400-new Date/1e3|0;w.innerText=[60,60,24,999].map(z=>(q='00'+d%z,d=d/z|0,q.slice(z<61?-2:-3))).reverse().join`:`")

<a id=w

Answer 16

C#, 142 bytes

using System;class P{static void Main(){a:Console.Write($"\r{(new DateTime(2019,3,31)-DateTime.Now).ToString("d\\:h\\:mm\\:ss  ")}");goto a;}}

Ungolfed program:

using System;
class P
{
    static void Main()
    {
        a: Console.Write($"\r{(new DateTime(2019, 3, 31) - DateTime.Now).ToString(@"d\:h\:mm\:ss  ")}"); goto a;
    }
}

Answer 17

Bash + GNU date, 128 bytes

2 bytes shaved off thanks to @muru, and 2 off earlier thanks to @This Guy.

C=:%02d;while sleep 1;do D=$[B=3600,A=24*B,1553990400-`date +%s`];printf "%03d$C$C$C\r" $[D/A] $[D%A/B] $[D%A%B/60] $[D%60];done

Ungolfed

DAY=86400
HOUR=3600
while sleep 1 ; do
 DIFF=$[1553990400-`date +%s`]
 printf "%03d:%02d:%02d:%02d\r" \
         $[DIFF/DAY] \
         $[DIFF%DAY/HOUR] \
         $[DIFF%DAY%HOUR/60] \
         $[DIFF%60]
done

Answer 18

Phooey, 101 bytes

-1(>"\e[H"~t/1000;1554004800@%60>&/60@%60>&/60@%24>&/24@@/100{$i}&/10{$i}&$i<(_1":"@/10{$i}&$i<)"
"#1)

\e represents the ESC nonprintable, hex 0x1B. Requires your average Linux terminal (and I believe it may work on Windows with a recent command prompt). Phooey does not support C-style escapes, the bytes must be verbatim or you must use $cN.

-1            # set sentinel cell
(             # do {..} while (*cell) (infinite loop)
  >           #   move past our sentinel
  "\e[H"     #   print "clear" ANSI escape code
  ~t          #   get current Unix time in milliseconds
  /1000       #   convert to seconds
  ;1554004800 #   31 Mar 2019 in Unix time - *cell
  @           #   Push a copy
  %60         #   Store seconds in the first cell
  >&          #   Move to the next cell
  /60         #   Convert to minutes
  @           #   Push a copy
  %60         #   Store minutes in the second cell
  >&/60@%24>  #   ya get the point
  &/24        #   get the number of days
  @@          #   begin ugly zero pad code
  /100{$i}    #   if intdiv(days, 100) == 0, print 0
  &/10{$i}    #   repeat for tens place
  &$i         #   print value
  <           #   go to hours place 
  (_1         #   do {..} while not -1 (our sentinel)
    ":"       #     print ":"
    @/10{$i}  #     zero pad
    &$i       #     print digit
    <         #     go to prev cell
  )           #   loop till sentinel
  "\n"       #   print new line to flush stdout
  #1          #   wait one second otherwise your terminal will flip out
)             # loop forever 

It does fail miserably for dates after Brexit thanks to signed division lul:

-689:0-8:-44:-37

But for dates before Brexit, it is correct.

For a version which sets to zero after Brexit, (at the cost of a memory leak and 9 bytes), here you go:

-1(>"\e[H"~t/1000;1554004800@@&2^{@}&@%60>&/60@%60>&/60@%24>&/24@@/100{$i}&/10{$i}&$i<(_1":"@/10{$i}&$i<)"
"#1)

Specifically, this code uses some fancy math to check for negative.

@@&2^{@}&

(Or *@ to patch the memory leak which pops, multiplies by zero, then pushes)

It uses the pow operator.

Specifically, ^ does this:

    *cell = (int64_t)pow(*cell, op);

So, in equivalent C, this code would be:

int64_t positive_or_zero(int64_t val)
{
    int64_t pwr = (int64_t)pow(2, val);
    if (pwr == 0) {
        val = pwr;
    }
    return val;
}

pow is a function which accepts and returns double, however, we downcast this.

People who are familiar with how double conversion works will know that infinity converts to 0x8000000000000000, and fractions between 0 and 1 will be zero.

Additionally, \${2}^{x}\$ will always be a number greater than 1 if \$x >= 0\$, and a positive fraction less than 1 if \$x < 0\$.

Therefore, if ^ returns 0, we know that \$x\$ is negative. Then, we just push it to the stack.

Answer 19

MATL, 45 bytes

737515`tZ'-tkwy-':HH:MM:SS'XOw'%03d'YDwYcDXxT

TIO apparently doesn't support clearing the output, but thankfully MATL Online does!

At 2 bytes more, a bit more CPU-friendly version that does a pause (sleep) every second:

737515`tZ'-tkwy-':HH:MM:SS'XOw'%03d'YDwYcDT&XxT

Try this on MATL Online

737515 is "31st of March 2019" represented MATLAB's default epoch format - number of days from January 0, 0000, optionally including a fractional part to represent the time of day. (I tried to shorten this by calculating it somehow, but its only factors are 5 and another six digit number (147503), and I couldn't figure out a way to do it in less than 6 bytes.)

`    % start do-while loop
tZ`- % duplicate Brexit date, get current date (& time), subtract
tk   % duplicate the difference, get the floor of it (this gives number of days left)
w    % switch stack to bring unfloored difference to top
y    % duplicate the floored value on top of that
-    % subtract to get fractional part representing time
':HH:MM:SS'XO % get a datestr (date string) formatted this way
w    % switch to bring number of days back on top
'%03d'YD      % format that to take 3 places, with 0 padding if needed
wYc  % switch to bring time string back on top, concatenate date and time
D    % display the concatenated result!
T&Xx % clear screen after a 1 second pause (the pause is optional, without it the call is `Xx`)
T    % push True on stack to continue loop

Answer 20

PHP, 64 bytes

while($d=1553990401-time())echo--$d/86400|0,date(":H:i:s\r",$d);

This will count exactly until 0:00:00:00 and then break/exit. Run with -r.

-2 bytes if I wouldn´t have to print the 0.

Answer 21

RPL, 83 78 bytes

Assuming your HP48, or similar, is setup with correct (UK) time and date, mm/dd date format, and 24h time format:

WHILE 1REPEAT DATE 3.302019DDAYS":"1.1 24TIME HMS- TSTR 15 23SUB + + 1DISP END

I was surprised to be able to save 2 bytes by removing spaces around ":". 1.1 is the shortest valid date, later dumped by SUB. Be careful with emulators, the time may run faster or slower (or not at all) than your wall clock. With a real HP, you can stop this program by pressing the ON key … or wait for empty batteries.

Answer 22

SlimSharp, 56 bytes

for(;;)P($"{TP("2019-3-31")-T.Now:ddd\\:hh\\:mm\\:ss}");

Answer 23

PHP, 102 95 90 bytes

Saved 7 bytes thanks to @TheLethalCoder & by not factoring

Saved another 5 bytes by concatenating

<? $b=1553990400-time();echo floor($b/$d=86400).date(':H:i:s', $b%$d);header('Refresh:1');

This is my first golf, so I'm probably missing quite a few tricks, but here you are regardless.

As for @chocochaos' PHP answer that would otherwise trump this, I believe it is flawed for reasons I have explained in my comments, but as I'm new here I might be wrong. Or I'm just a newbie :)

Answer 24

AWK, 78 bytes

BEGIN{for(;v=1552953600-systime();printf"\r%d:%s",v/86400,strftime("%T",v)){}}

Try it online!

Was longer before I realized I could precalculate the end time. Sometimes it pays to be a bit late to the game and get ideas from others.

FYI, the TIO link doesn't work very well, since it doesn't implement \r properly.

Answer 25

F#, 142 bytes

open System
let f=
 let t=DateTime(2019,3,31)
 while DateTime.Now<=t do Console.Clear();t-DateTime.Now|>printf"%O";Threading.Thread.Sleep 1000

I grew up in Ireland about half a kilometre from the border. Apart from a "Welcome to Fermanagh" sign and the road markings changing you wouldn't know you'd entered another country. Used to cross it twice on the way to school.

Answer 26

c, gcc 114 bytes

main(s){system("clear");if(s=1553900399-time(0)){printf("%d:%d:%d:%d\n",s/86400,s/3600%24,s/60%60,s%60);main(s);}}

Nothing omitted, full program. The program compiles in gcc on Ubuntu. The countdown will not show a long trail of print statements because of the system call to clear and halts when the countdown reaches 0 seconds.

UnGolfed

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>


//Brexit countdown timer
int main(){
  int sec = 1553900400 - time(0);//seconds remaining until Brexit
  if(sec){
    sleep(1);
    system("clear");
    printf("Brexit Countdown\n");
    printf("days Hours Mins Secs\n");
    printf("%d:  %d:    %d:  %d\n",
            sec/86400, sec/3600%24,
            sec/60%60, sec%60);
    main();
  }
}