Re: Help with some clever bit operations

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Robert Cummings wrote:
> On Tue, 2006-06-13 at 06:22, Jochem Maas wrote:
>> My brain needs a crutch when trying doing this kind of thing
>> (normally I only write hex number literally when dealing with bitwise stuff -
>> the conversion stuff still makes my head spin) - this is what this table is for:
>>
>> 128 64 32 16 8 4 2 1
>> 1   0  1  1  0 1 0 1
>> 0   1  0  1  1 1 0 0
>> 0   0  0  0  1 1 1 1
>>
>> and then I did this - hopefully it shows what you can/have to do:
>>
>> <?php
>>
>> // set some values
>> $oldval = 128 + 32 + 16 + 4 + 1; // 10110101
>> $update = 64 + 16 + 8 + 4;	 // 01011100
>> $mask   = 8 + 4 + 2 + 1;	 // 00001111
> 
> You could just do the following:
> 
> $oldval = bindec( '10110101' );
> $update = bindec( '01011100' );
> $mask   = bindec( '00001111' );

when I was writing the reply I played with about 5 different
conversion funcs - pretty everything expect bindec() !!!

I guess i was being lazy - but then I alway think directly in hex numbers
when doing bitwise stuff (at least I use hex notation for the constant value
that I almost invariably end up creating)

anyway cheers for the lightbuld moment :-)

> 
> Cheers,
> Rob.

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