Minimiscience's Code Snippets

Tabs-to-space function

This Perl function returns its argument with any tabs it contained converted into the appropriate number of spaces.

sub tabs2space($) {
 my $str = shift;
 1 while $str =~ s/\t+/' ' x (length($&)*8 - length($`)%8)/e;
 return $str;
}

to perl text text formatting by Minimiscience on Jul 06, 2007

basename & dirname in Perl

These two Perl functions implement approximations of the UNIX utilities `basename` and `dirname`, though basename() automatically strips off the last extension no matter what.

sub basename($) {
 my $file = shift;
 $file =~ s!^(?:.*/)?(.+?)(?:\.[^.]*)?$!$1!;
 return $file;
}

sub dirname($) {my $file = shift; $file =~ s!/?[^/]*/*$!!; return $file; }

to unix files perl directory filesystem file extension by Minimiscience on Jul 06, 2007 1 Comments

This shell script reads in a NetHack logfile & outputs a list of all the things that have killed you, with their frequencies.

This script was originally posted to rec.games.roguelike.nethack by Faux_Pseudo.

grep killed /usr/games/lib/nethackdir/logfile | awk -F killed '{print"killed"$NF}' | sort | uniq -c | sort -r

to unix shell games NetHack by Minimiscience on Jul 05, 2007

Unicode chart

This PHP-enhanced HTML page will display the first 4,096 (unless you change it) Unicode characters in a neat table. Your browser's ability to render the characters properly may vary.

<HTML>
<HEAD>
<TITLE>Unicode Chart</TITLE>
<LINK REL="Stylesheet" TYPE="text/css" HREF="styles.css">
<STYLE TYPE="text/css">
TH {text-align: center; }
TD {text-align: center; }
</STYLE>
</HEAD>
<BODY>
<TABLE ALIGN=CENTER BORDER=1>
<TR><TH> </TH><TH>0</TH><TH>1</TH><TH>2</TH><TH>3</TH><TH>4</TH><TH>5</TH><TH>6</TH><TH>7</TH><TH>8</TH><TH>9</TH><TH>A</TH><TH>B</TH><TH>C</TH><TH>D</TH><TH>E</TH><TH>F</TH></TR>
<?PHP
 for ($i=0; $i<256; $i++) { //DON'T try to generate the whole chart
  printf('<TR><TD>%04X</TD>', $i);
  for ($j=0; $j<16; $j++) {
   printf('<TD>&#x%X%X;</TD>', $i, $j);
  }
  echo "</TR>\n";
 }
?>
</TABLE>
</BODY>
</HTML>

to html php unicode chart by Minimiscience on Jul 05, 2007

Image aggregator

This PHP snippet outputs the contents of a table (beginning & ending tags not included) containing all the images from the current directory.

<?PHP
 $columns = 3;
 $im = glob("*.{gif,jpg,png}", GLOB_BRACE);
 $rows = ceil(count($im) / $columns);
 for ($i = 0; $i < $rows; $i++) {
  echo "\n<TR>";
  for ($j = $columns*$i; isset($im[$j]) && $j - $columns*$i < $columns; $j++) {
   echo "<TD>$im[$j]<BR><IMG SRC='$im[$j]'></TD>";
  }
  echo "</TR>";
 }
?>

to files php images directory glob filesystem by Minimiscience on Jul 05, 2007

Fibonacci function

This function returns the nth Fibonacci number, though most platforms can go no higher than the 47th.

int Fibonacci(int n) {
 int a = 1, b = 1, c, i;
 for (i=3; i<=n; i++) {c = b; b += a; a = c; }
 return b;
}

to c math by Minimiscience on Jul 04, 2007

Factorial function

A (non-recursive) factorial function

int factorial(int x) {
 int fac = 1;
 for (int i=2; i<=x; i++) fac *= i;
 return fac;
}

Also, with this function defined, you can use two macros for calculating combinations & permutations:

#define nCr(n, r) (factorial(n) / factorial(n-r) / factorial(r))
#define nPr(n, r) (factorial(n) / factorial(n-r))

to c math combinations permutations by Minimiscience on Jul 04, 2007

Modular inverse function

This function calculates & returns the inverse of a modulo n, both of which should be positive. If the inverse does not exist, 0 is returned. If you don't know what this means, don't bother.

int modInverse(int a, int n) {
 int i = n, v = 0, d = 1;
 while (a>0) {
  int t = i/a, x = a;
  a = i % x;
  i = x;
  x = d;
  d = v - t*x;
  v = x;
 }
 v %= n;
 if (v<0) v = (v+n)%n;
 return v;
}

to c math modulus by Minimiscience on Jul 04, 2007

Greatest Common Denominator function

This function returns the greatest common denominator (GCD) of its arguments.

int gcd(int x, int y) {
 int a, b;
 if (x<y) {a = y; b = x; }
 else if (x>y) {a = x; b = y; }
 else {return x; }
 do {
  int r = a % b;
  a = b;
  b = r;
 } while (b != 0);
 return a;
}

to c math GCD by Minimiscience on Jul 04, 2007

Code execution timer

These two bits of code can be used to record & output the execution time of a piece of code in microseconds. NOTE: The functions used here are only available on BSD-like systems (I think).

/* Put this line at the top of the file: */
#include <sys/time.h>

/* Put this right before the code you want to time: */
struct timeval timer_start, timer_end;
gettimeofday(&timer_start, NULL);

/* Put this right after the code you want to time: */
gettimeofday(&timer_end, NULL);
double timer_spent = timer_end.tv_sec - timer_start.tv_sec + (timer_end.tv_usec - timer_start.tv_usec) / 1000000.0;
printf("Time spent: %.6f\n", timer_spent);

to c unix time timer performance testing BSD by Minimiscience on Jul 04, 2007

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