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php3-list | 199901

Re: [PHP3] size of int = ((2^32) / 2) - 1? From: Sascha Schumann (sas <email protected>)
Date: 01/31/99

On Sun, Jan 31, 1999 at 05:40:59AM -0700, Joey Smith wrote:
> Rasmus:
> Is the max size of int:
> 2147483647?

It is the biggest number which is representable by using a 32bit signed
integer.

> That's, what, 2 billion or so?

We German say Milliarden :-)

> The best I could figure, that makes it
> ( 2^32 )
> (---------) - 1
> ( 2 )
>
> Am I right?

It's the same as 2^31 - 1

>
> (I just wrote a script that said:
> <?$i = 65537; /* The standard value of an int, right? */

Standard value? 65537 is 2^16 + 1, you probably mean a word... but remember
that there were platforms with 10-bits per byte and 20-bits per word (instead
of 16).

> while (is_int($i)) {$i++;}
> exit;
> ?>
>
> And piped the results to an external file. When it freaked,
> and started printing negatives, I subtracted 1, and tested it.
> It seems right...
>
> A few ?'s...
> Was there an easier way i could have done this?

Yes.

> Why didn't the script exit when it hit 2147483648,
> instead of going to -2147483648?

That is the way how signed integer numbers work. The highest bit is used to
represent signedness. 

-- 
                     
          Regards,
						                                
                            Sascha Schumann | 
                                 Consultant | finger sas <email protected>
                                            | for PGP public key

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