DZone Snippets: comparison code

String equality tester

Minimiscience (Guildorn Tanaleth) — Thu, 05 Jul 2007 03:22:26 GMT

If you want to test the equality of two strings and don't want the overhead of strcmp(), then this is the function for you.



_Bool strequals(char* a, char* b) {

 if (!a || !b) return 0;

 do {if (*a != *b) return 0; } while (*a++ && *b++);

 return 1;

}

JavaScript String Comparison

thitiv (Thiti V. Sintopchai) — Fri, 09 Feb 2007 09:13:11 GMT

// Example use
// if (isSameString(tags, "_none_")) ...



      function isSameString( s1, s2 )

      {

        alert( "s1: " + s1.toString() );

        alert( "s2: " + s2.toString() );



      	if ( s1.toString() == s2.toString() )

        {

      	  return true;

        }

        else

        {

          return false;

        }

      }

Is a value between two other values?

gregg.irwin (Gregg Irwin) — Wed, 01 Mar 2006 03:52:31 GMT



between?: func [

    value bound-1 bound-2

    /exclusive

    /local low-bound high-bound

][

    set [low-bound high-bound] sort reduce [bound-1 bound-2]

    either exclusive [

        all [(value > low-bound) (value < high-bound)]

    ][

        ;-- Inclusive comparison

        all [(value >= low-bound) (value <= high-bound)]

    ]

]

limit - limit a value between boundary values

gregg.irwin (Gregg Irwin) — Wed, 01 Mar 2006 03:49:08 GMT



limit: func [

    "Make sure val falls between lower and upper bounds, inclusive"

    val lower upper

][

    max min val upper lower

]

All Exceptions Created Equal

CloCkWeRX (Daniel O'Connor) — Fri, 17 Feb 2006 10:01:44 GMT

All exceptions are created equal. But what if you have a very good and pressing reason to serialize one to save it in a database? For instance, you had a collection of checks you wanted to run against some data, and save the results?

Ah, that's easy! serialize() was made for that! So off you trot, you make a few changes to the code, add a blank line here, a blank line there, and suddenly your code can't find the exact matches of the serialized object in the database.

HUH? What's going on? You're the exact same Exception I just threw three minutes ago, and you've sporadically broken?

It took me a while to twig. When you create an exception ($e = new Exception("foo");), it's shiny and new and listens when you do equality comparisions (==).

But things go awry: you throw a new Exception from your filter, catch it, and serialize it. You haven't remembered that...



$a = new Exception("foo");

try {

    throw $a; //Line 1

} catch (Exception $e) {

    throw $a; //Line 10;

}

will result in two difference traces. One saying "I was thrown on on line 1", the other "I was thrown on on line 10"...

Fuck oath, hello stupid coder. You've been wracking your brains wondering why every time you go off and edit a different bit of code it serializes differently; and there you have it.

How the hell do I fix it? Going to __sleep() on the job actually helps.



class DumbException extends Exception {

    /**

     * Cleanup anything we need before serialisation

     *

     * @return  string[]    An array of member varible names to serialize

     * @see     http://php.planetmirror.com/manual/en/language.oop5.magic.php

     */

    public function __sleep() {

        return array('string','code');

    }



    /**

     * Compare against another DumbException for equality.

     *

     * Since two exceptions can be !== because the trace / line / file

     * information is different, we need to do this.

     */

    public function cmp(DumbException $e) {

        return (serialize($e) == serialize($this));

    }

}



print '';

$a = new DumbException();

$b = new DumbException();





try {

    try {

        throw $b;

    } catch (Exception $e) {

        throw $a;

    }

} catch (Exception $e) {



    var_dump($a === $b);

    var_dump($a == $b);

    var_dump($b === $e);

    var_dump($b == $e);

    var_dump($a === $e);

    var_dump($a == $e);



    var_dump($b->cmp($e));

    var_dump($a->cmp($e));

}

print '';

?>

Comparing path.py with os.path

korakot (Korakot Chaovavanich) — Sun, 12 Feb 2006 20:08:53 GMT

Taken from Simon Willson's blog post.



# with os.path.walk

def delete_backups(arg, dirname, names):

    for name in names:

        if name.endswith('~'):

            os.remove(os.path.join(dirname, name))



os.path.walk(os.environ['HOME'], delete_backups, None)



# with os.path, if (like me) you can never remember how os.path.walk works

def walk_tree_delete_backups(dir):

    for name in os.listdir(dir):

        path = os.path.join(dir, name)

        if os.path.isdir(path):

            walk_tree_delete_backups(path)

        elif name.endswith('~'):

            os.remove(path)



walk_tree_delete_backups(os.environ['HOME'])



# with path

dir = path(os.environ['HOME'])

for f in dir.walk():

    if f.isfile() and f.endswith('~'):

        os.remove(f)

Comparing pygame and pys60

korakot (Korakot Chaovavanich) — Fri, 10 Feb 2006 20:34:56 GMT

I take the pygame code from here. Then, write my own pys60 part.



# pygame's typical beginning

import pygame

from pygame.locals import *



# pys60

import e32, graphics

from appuifw import *

Setting up the screen



# pygame

window = pygame.display.set_mode((468, 60)) 



# pys60

app.screen = 'full'   # or 'normal', 'large'

Get screen or canvas



# pygame

screen = pygame.display.get_surface() 



# pys60

app.body = canvas = Canvas(None, key.handle_event) 

# you need to create key (a Keyboard instance) before this

Loading image



# pygame

monkey_image = pygame.image.load(file_name)



# pys60

monkey_image = graphics.Image.open(file_name)

Drawing image onto the screen



# pygame

screen.blit(monkey_image, (0,0))

pygame.display.flip()  



# pys60

canvas.blit(monkey_image, target=(0,0))

# we may add a buffer, which will need buffer.blit(image)

# and canvas.blit(buffer) for equivalent steps

Loading and playing sound



# pygame

sound = pygame.mixer.Sound(fullname)

sound.play()



# pys60

import audio

sound = audio.Sound.open(fullname)

sound.play()

For Rect and Sprite, there is no pys60 equivalence yet.
I may write an equivalent class someday.