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<?php

/*
    A Demonstration of the PHP BC Library
    
        How to use really big numbers in PHP
    
    Usage:
        path/to/bc_demo.php
    
    Reference
        http://www.php.net/manual/en/ref.bc.php

*/

$max = 1000;
foreach ( range(1,$max) as $x )
{
    if (
        ! ( pow(2,$x)+1 > pow(2,$x) ) ||
        ! ( pow(2,$x)-1 < pow(2,$x) ) ||
        ! ( pow(2,$x-1)*2 == pow(2,$x) )         
    ) break;
}

$maxpow = $x-1;
$maxint = bcpow(2, $maxpow);
$Result['op'] = "max supported int: 2^$maxpow or $maxint\n";


foreach ( range(1,$max) as $x )
{
    if (
        ! ( bccomp(bcadd(bcpow(2,$x),1), bcpow(2,$x)) == 1 ) ||
        ! ( bccomp(bcsub(bcpow(2,$x),1), bcpow(2,$x)) == -1 ) ||
        ! ( bccomp(bcmul(bcpow(2,$x-1),2), bcpow(2,$x)) == 0 )
    ) break;
}

$maxpow = $x-1;
$maxint = bcpow(2, $maxpow);
$Result['bc'] = "max supported int >= 2^$maxpow or $maxint\n";

printf("<pre>%s</pre>", print_r($Result,1));

?>