#CarolsInCode - Top Five Countdown

#CarolsInCode is a programming meme with a seasonal twist. Short programs are used to encode the lyrics of a Christmas carol. Some display the lyrics when the program runs while the more ingenious examples define the song with the program's control structures.

For example in JavaScript:

while ( shepherds.watch() == 'flocks' &&
  date.getHours() in night )
{
  lord.angel--;
  glory.shone_around();
}

This is While Shepherds Watched Their Flocks by Nahum Tate:

“While Shepherds watch their flocks by night,
All seated on the ground,
The angel of the Lord came down,
And glory shone around.”

Here's the top five countdown of the very best #CarolsInCode. Can you identify all five? Is your favourite missing?

GrumpyWookie:

Weather.Outside="frightful";
Fire.Delightful=true;
Lights.Luminosity=WayDownLow;
for (int i=1; i<=3; i++) { LetItSnow(); }

ShinyEmptyHead:

public Sleigh sleigh;
public void dashThroughSnow()
{
int horses = 1;
sleigh = new Sleigh(horses);
for (Field field : fields)
{
laugh();
}
}

JohnGirvin:

var wenceslas = new Person({
    rank: 'king',
    alignment: 'good'
});
$.bind(FeastOfStephen, function() {
    wenceslas.lookOut();
});

Costall:

if (DateTime.Now()=="25/12/2010")
{
for (i=0;i<3;i++) Ship[i].Visibility = Visibility.Visible;
}

GrumpyWookie:

Kiss.PersonA="Mummy";
Kiss.PersonB="Santa";
Kiss.Witness=Me;
Kiss.Location=Mistletoe.Underneath;
Kiss.Time=Date.LastNight;

More #CarolsInCode

• #carolsincode - Christmas for Programmers
• carols in code | wee doors banging
• Carols in Code, A Festive Twitter Meme
• #CarolsInCode search on Twitter

#carolsincode - Christmas for Programmers

#carolsincode are small pseudo-programs which contain a Christmas song. Some examples display the lyrics while others use the program's control structures to define the song.

Here are five examples in C, CSS and JavaScript. Can you do better? ;-)

var kings=new Array(3);
for (x in kings)
{
  kings[x].origin='orient';
  kings[x].bearingGift=true;
  kings[x].travelled='afar';
}

main() {
  int a;
  for (a=1;a<5;a++) printf("Noel, ");
  printf("Born is the King of Israel.");
}

#rudolf .nose {
  color: red;
  background: url('very_shiny.jpg');
}

while ( shepherds.watch() == 'flocks' &&
  date.getHours() in night )
{
  lord.angel--;
  glory.shone_around();
}

for ( c=1, c<=4, c++)
{
  noel()
};
king = new Object();
king.kingdom = 'Israel';

Programming Contest: Topswaps

Al Zimmermann's latest programming challenge asks up to arrange a deck of n cards numbered 1 .. n to maximise the number of swaps. Each swap looks at the value x on the top card and reverses the top x cards.

For n=4 the sequence 3, 1, 4, 2 requires 4 swaps:

3

1

4

2

4

1

3

2

2

3

1

4

3

2

1

4

1

2

3

4

Al challenges us to find the best solution for the first 25 primes, n=2, 3, 5 .. 97. Even a simple program which tests random combinations can throw out some reasonable scores:

10 rem setup array
20 input z
30 dim x(z)
40 for a=1 to z
50 x(a)=a
60 next a
70 h=0

100 rem shuffle array
110 for a=1 to z
120 r=int(rnd*z+1)
130 t=x(a)
140 x(a)=x(r)
150 x(r)=t
160 next a

200 rem remember order
210 a$=""
220 for a=1 to z
230 a$=a$+","+str$(x(a))
240 next a

300 rem swap until done
310 c=0

400 q=x(1)
410 for a=1 to int(q/2)
420 t=x(a)
430 x(a)=x(q+1-a)
440 x(q+1-a)=t
450 next a

500 c=c+1
510 if x(1)>1 then goto 400

600 rem display highscore
610 if c>h then h=c:print c;" : ";a$
620 goto 100

Are you planning to take part in the contest?