DZone Snippets: swap code

Pointer swap function

rasmus (Rasmus Frederiksen) — Wed, 23 Apr 2008 10:39:53 GMT

// A generic pointer swap function that works with all structs by calling swap(&A, &B), where A and B are struct pointers



void swap(void **x, void **y) {

	void *t = *x;

	*x = *y;

	*y = t;

}

swap values without temporary variable

nevadalife (nevada) — Sat, 23 Sep 2006 17:40:36 GMT

The XOR swap algorithm is an inefficient method of swapping two variables. http://en.wikipedia.org/wiki/Xor_swap_algorithm



void XORSwap(void *x, void *y)

{

   *x ^= *y;

   *y ^= *x;

   *x ^= *y;

}

javascript image swap using DOM

Will_Rickards (Will Rickards) — Tue, 28 Feb 2006 04:31:16 GMT

Here is a javascript image swap that uses the DOM methods.
It uses them to support swapping images with different sizes.
Just changing the src property causes the swapped images to be distorted in IE.
This script uses replaceChild instead.



var blnDOMSUPPORT = (document.getElementById) ? true : false;

window.onload = window_load;



function window_load()

   {



   if ( blnDOMSUPPORT )

      {



      document.getElementById('icon1').onclick = swapimage;

      document.getElementById('icon2').onclick = swapimage;

      document.getElementById('icon3').onclick = swapimage;

      

      }

   else

      {



      document.images['icon1'].onclick = swapimage;

      document.images['icon2'].onclick = swapimage;

      document.images['icon3'].onclick = swapimage;



      }



   }



function swapimage()

   {

   

   if ( blnDOMSUPPORT )

      {



      var imgMain = document.getElementById('mainimage');

      var divParent;



      // create new image element

      var imgNew = document.createElement('img');



      // give it an image

      // here I use the src of the icon just for convenience

      // you'd want to somehow determine the src of your desired image

      imgNew.src = this.src;

   

      // give it an id

      imgNew.id = 'mainimage';



      // replace image

      divParent = imgMain.parentNode;

      divParent.replaceChild(imgNew, imgMain);



      }

   else

      {



      // old school image swap

      document.images['mainimage'].src = this.src;



      alert( 'old school' );



      }

   

   }

It would be used with HTML like this

Swap elements of an array in Ruby

peter (Peter Cooperx) — Fri, 13 May 2005 09:29:45 GMT

class Array

    def swap!(a,b)

         self[a], self[b] = self[b], self[a]

    self

    end

end

You can now do stuff like..

[1,2,3,4].swap!(2,3) # = [1,2,4,3] etc..

Many thanks to Sam Stephenson and technoweenie for their suggestions.