[BNM] Advice on Comparing base64 encoded images in PHP please.

[paul perrin]

To be really efficient...

If you can get under the hood of your interpreter, then you may find an
optimisation that allows you to operate on the two strings as a sinlge
processing instruction... comparing long strings should equate to a big
boolean 'and' - something that CPUs excel at :-).

This makes some assumptions on how PHP holds strings etc...

Paul /)/+)

On 02/07/07, John Montgomery <john at littlespikeyland.com> wrote:
>
> > if(md5($imageStr1) != md5($imageStr2))
>
> Is going to compute the md5's for both strings, so if you just want
> to know if the two strings are different it's going to be slower than
> using a strcmp.  Of course if you computed the md5's before hand and
> stored them (and kept them up-to-date) along with the base64 strings
> it would be quicker.
>
> Though, unless you're actually having speed problems you'd be far
> better off just keeping your code simple and sticking with strcmp (or
> surely just a plain old == assuming this is PHP?).
>
> cheers,
>        John
>
> On 2 Jul 2007, at 17:46, joseppi c wrote:
>
> > Hi,
> >
> > I am having to store jpeg Images as base64 encoded strings.
> >
> > I would like to do a comparison between two images to see if they
> > differ.
> >
> > Should I just do a:
> >
> > if(strcmp($imageStr1, $imageStr2))
> > {
> >  //do stuff
> > }
> >
> > Or speed-wise is it better to compare the MD5 result of each string:
> >
> > if(md5($imageStr1) != md5($imageStr2))
> > {
> >  //do stuff
> > }
> >
> > Or does it matter?
> >
> >
> > Thanks,
> >
> > Joe.
> >
> >
> >
> >
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