DZone Snippets: base code

How to call a base class method

jrobertson (James Robertson) — Sat, 02 Feb 2008 00:51:59 GMT

This Ruby example demonstrates using the keyword super to call the superclass method.



class Claw

  def grab(item)

    puts item + ' grabbed'

  end

end



class Hand < Claw

  def grab(item)

    super(item)

  end

end



h = Hand.new

h.grab('apple')

output



apple grabbed

for more information: http://www.google.com/search?q=ruby+keyword+super

Custom base conversion (to and from)

devijvers (Steven Devijver) — Sun, 30 Sep 2007 23:44:48 GMT

Handy to store large numbers in a shorter notation. Doesn't work with negative numbers (for negative numbers you need to store an additional byte to indicate a positive or negative value, pass the absolute value).



	private static final short BASE_40_RADIX = 40;

	private static final short BASE_40_BASE = 48;

	private static final String BASE_40_ZERO = "0";



	public static long fromBase40(char[] cs) {

		return fromBase(cs, BASE_40_BASE, BASE_40_RADIX);

	}



	public static char[] toBase40(final long i) {

		return toBase(i, BASE_40_BASE, BASE_40_RADIX, BASE_40_ZERO);

	}



	private static final short BASE_75_RADIX = 75;

	private static final short BASE_75_BASE = 48;

	private static final String BASE_75_ZERO = "0";



	public static long fromBase75(char[] cs) {

		return fromBase(cs, BASE_75_BASE, BASE_75_RADIX);

	}



	public static char[] toBase75(final long i) {

		return toBase(i, BASE_75_BASE, BASE_75_RADIX, BASE_75_ZERO);

	}



	private static final short BASE_90_RADIX = 90;

	private static final short BASE_90_BASE = 33;

	private static final String BASE_90_ZERO = "!";



	public static long fromBase90(char[] cs) {

		return fromBase(cs, BASE_90_BASE, BASE_90_RADIX);

	}



	public static char[] toBase90(final long i) {

		return toBase(i, BASE_90_BASE, BASE_90_RADIX, BASE_90_ZERO);

	}



	private static char[] toBase(final long i, final short base, final short radix, String nullCharacter) {

		long value = i;



		if (value == 0) {

			return nullCharacter.toCharArray();

		}



		String result = "";

		while (value > 0) {

			long mod = value % radix;

			value -= mod;

			if (value > 0) value /= radix;

			result = (char)(mod + base) + result;

		}



		return result.toCharArray();

	}



	private static long fromBase(char[] cs, final short base, final short radix) {

		long value = 0;

		for (int i = cs.length - 1; i >= 0; i--) {

			int digit = ((int)cs[i]) - base;

			if (digit < 0 || digit >= radix) {

				throw new IllegalArgumentException("Invalid Base" + radix + " character: " + cs[i]);

			}

			long digitBase = (long)Math.pow(radix, (cs.length - 1) - i);

			value = (digit * digitBase) + value;

		}



		return value;

	}

And here are some tests:



	public void testFromBase40() {

		assertEquals(2559999, NumberUtils.fromBase40("WWWW".toCharArray()));

		assertEquals(1117580, NumberUtils.fromBase40("ABCD".toCharArray()));



		assertEquals(0, NumberUtils.fromBase40("0".toCharArray()));

		assertEquals(1, NumberUtils.fromBase40("1".toCharArray()));



		assertEquals(40, NumberUtils.fromBase40("10".toCharArray()));

		assertEquals(80, NumberUtils.fromBase40("20".toCharArray()));



		assertEquals(41, NumberUtils.fromBase40("11".toCharArray()));

		assertEquals(81, NumberUtils.fromBase40("21".toCharArray()));



		assertEquals(81, NumberUtils.fromBase40("0021".toCharArray()));



		assertEquals(3061560805L, NumberUtils.fromBase40("MSTSD5".toCharArray()));

	}



	public void testToBase40() {

		assertEquals("0", new String(NumberUtils.toBase40(0)));

		assertEquals("1", new String(NumberUtils.toBase40(1)));



		assertEquals("10", new String(NumberUtils.toBase40(40)));

		assertEquals("20", new String(NumberUtils.toBase40(80)));



		assertEquals("11", new String(NumberUtils.toBase40(41)));

		assertEquals("21", new String(NumberUtils.toBase40(81)));



		assertEquals("ABCD", new String(NumberUtils.toBase40(1117580)));

		assertEquals("WWWW", new String(NumberUtils.toBase40(2559999)));



		assertEquals("MSTSD5", new String(NumberUtils.toBase40(3061560805L)));



	}



	public void testToBase90() throws Exception {

		assertEquals("#Q&Y.`QY#", new String(NumberUtils.toBase90(10908158098650842L)));

	}



	public void testFromBase90() throws Exception {

		assertEquals(10908158098650842L, NumberUtils.fromBase90("#Q&Y.`QY#".toCharArray()));

	}

bindec.scm

mcandre (Andrew Pennebaker) — Thu, 08 Feb 2007 03:21:50 GMT

// Convert list of 1s and 0s back to base ten number.



; Andrew Pennebaker

; 5 Feb 2007

; License: GPL

; URL: http://snippets.dzone.com/posts/show/3479



(define bin->dec

	(lambda (b)

		(cond

			((integer? b) b)

			((= (length b) 0) 0)

			(else

				(+

					(* (expt 2 (- (length b) 1)) (car b))

					(bin->dec (cdr b)))))))

decbin.scm

mcandre (Andrew Pennebaker) — Thu, 08 Feb 2007 03:18:23 GMT

// Converts a base ten integer to a list of 1s and 0s



; Andrew Pennebaker

; 3 Feb 2007

; License: GPL

; URL: http://snippets.dzone.com/posts/show/3478



(define dec->bin

	(lambda (d)

		(cond

			((< d 1) (list 0))

			((= d 1) (list 1))

			((> d 1) (append

				(dec->bin (floor (/ d 2)))

				(list (if (= (modulo d 2) 0) 0 1)))))))

Generic base conversor //Javascript Object

jonasraoni (Jonas Raoni Soares Silva) — Fri, 29 Jul 2005 17:22:24 GMT

Minimum Common Multiple

[UPDATED CODE AND HELP CAN BE FOUND HERE]



//+ Jonas Raoni Soares Silva

//@ http://jsfromhell.com/number/base-conversor [v1.0]



Conversor = {

	h: '0123456789abcdefghijklmnopqrstuvwxyz',



	int2base: function( n, base ){

		if( base < 2 || base > this.h.length )

			throw new Error( "base inválida" );

		for( var n = parseInt( n ) || 0, result = ""; n; result = this.h.charAt( n % base ) + result, n = Math.floor( n / base ) );

		return result;

	},

	base2int: function( s, base ){

		for( var i = -1, l = s.length, result = 0; ++i < l; result = result * base + this.h.indexOf( s.charAt( i ) ) );

		return result;

	}

}

baseX converter

toxi (karsten schmidt) — Tue, 19 Jul 2005 19:55:29 GMT

you can use this function to convert an integer into any number system upto base36 (e.g. for TinyURL generation coupled with a global ID counter)

function int2baseX($val,$base=16) {

  if (0==$val) return 0;

  $symbols='0123456789abcdefgihjklmnopqrstuvwxyz';

  $result='';

  $exp=$oldpow=1;

  while($val>0 && $exp<10) {

    $pow=pow($base,$exp++);

    $mod=($val % $pow);

    $result=substr($symbols,$mod/$oldpow,1).$result;

    $val-=$mod;

    $oldpow=$pow;

  }

  return $result;

}