[mapguide-users] Issues selecting a feature with custom coding

[Kenneth, GEOGRAF A/S]

There is a simple algorithm here:
http://en.wikipedia.org/wiki/Base64

My PHP is a bit too rusty to comment on the correctness of your code.

Basically Base64 works, by encoding each 6 bits into a character.
That means it produces 4 bytes per 3 input bytes, and always pads up 
with =, to produce a string of a length divisible by 4.
I _think_ the strings ID columns are encoded as an UTF-8 byte array into 
Base64.

Regards, Kenneth, GEOGRAF A/S



nclayton skrev:
> I have created this function in php which gives me the correct value for
> 33181 ("nYEAAA==") but I would like for another pair of eyes (or 20) to see
> if this is solid and if it can be simplified.
>
> function MgBase64_encode($value){
> 	$key="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
> 	$dhv = dechex($value);
> 	$grp = (strlen($dhv) / 2);
> 	$arr = array();
> 	for($i=0;$i<$grp;$i++){
> 		$arr[$i] = substr($dhv,($i * 2),2);
> 	}
> 	$arr = array_reverse($arr);
> 	$bvl = decbin(hexdec(join("",$arr)));
> 	$chk = (strlen($bvl) % 6);
> 	if($chk > 0){ $bvl = str_pad($bvl,(strlen($bvl) + (6 - $chk)),'0'); }
> 	$grp = (strlen($bvl) / 6);
> 	$arr = array();
> 	for($i=0;$i<$grp;$i++){
> 		$arr[$i] = substr($key,bindec(substr($bvl,($i * 6),6)),1);		
> 	}
>
> 	return str_pad(join("",$arr),6,'A') . "==";
> }
>
>
> Nick
>
>
>
>
> nclayton wrote:
>   
>> Thank you for the reply and the link. I'd actually read that post, but it
>> gave me a bit of a headache trying to reverse the process...I'm rather new
>> to this mode of thinking (i avoided it as long as i could).
>>
>> As far as the parcel number value is concerned, it needs to be a string
>> because they are different for each county that we deal with and are
>> typically 14-22 alphanumeric characters in length, such as
>> '1-023B-001.000'
>>
>> Nick
>>
>>
>> JasonBirch wrote:
>>     
>>> More details on this here:
>>>
>>> http://tinyurl.com/2rrq3e
>>>
>>> I'm definitely a bit rusty on this stuff, but in your initial problem
>>> are you sure you want to be using a string value for the parcel id?
>>>
>>> Jason
>>>
>>> -----Original Message-----
>>> From: nclayton
>>> Subject: Re: [mapguide-users] Issues selecting a feature with custom
>>> coding
>>>
>>> Here are the results of both the mgos base64 value and the php
>>> base64_encode
>>> value:
>>>
>>> Actual FeatId: 33181
>>> MGOS Value: nYEAAA==
>>> base64_encode Value: MzMxODE=
>>>
>>> I found code for writing a base64 function in javascript, and it gives
>>> the same result as the php function.
>>> _______________________________________________
>>> mapguide-users mailing list
>>> mapguide-users at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/mapguide-users
>>>
>>>
>>>       
>>     
>
>   
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