Because you just can't get enough self-reproducing code...



Tobias from PHPwizard wrote me regarding an earlier blog entry on self-reproducing code. He uses a printf to achieve the necessary recursion for self-reproduction. Way, way more elegant than the clunky approach I wrote over lunch one day. Anyhow, here 'tis:



I used these as signatures back in 1999 or 2000:



<?$p = '<?$p = %c%s%c; printf($p,39,$p,39);?>'; printf($p,39,$p,39);?>



Another self-printing signature:



<?printf("<?".$a='printf("<?".$a=%c%s%c,39,$a,39);?>',39,$a,39);?>



This is unrelated, but cool: :)

Mandelbrot, takes less than a second with PHP 5.0, took 3.5 seconds to execute with PHP 4.0.1 and 13.5 seconds with 3.0:



<?$c=$s=0;$a=$t=$x=$y=$b=-2;for(;$b-=$a>2?0.1/($a=-2):0,$b<2;

$s.=chr(30+$c),$a+=0.0503)for($x= /* Tobias Ratschiller */

$y=$c=0;++$c<90&$x*$x+$y*$y<4;$y= /* http://phpWizard.net */

2*$x*$y+$b,$x=$t)$t=$x*$x-$y*$y+$a;print(chunk_split($s,80));?>