在PHP中我怎么能有一个64位的整数?
它似乎不是通过配置文件,而是可能是一个编译时选项,它取决于平台。
发布于 2009-05-14 16:35:04
本机64位整数需要64位硬件和64位版本的PHP。
在32位硬件上:
$ php -r 'echo PHP_INT_MAX;'
2147483647
在64位硬件上:
$ php -r 'echo PHP_INT_MAX;'
9223372036854775807
发布于 2009-05-14 15:35:53
PHP int大小与平台相关。有一个名为unpack()的函数,它基本上允许将不同类型的数据从二进制字符串转换为PHP变量。似乎将其存储为64位的唯一方法是将其存储为字符串。
/// portably build 64bit id from 32bit hi and lo parts
function _Make64 ( $hi, $lo )
{
// on x64, we can just use int
if ( ((int)4294967296)!=0 )
return (((int)$hi)<<32) + ((int)$lo);
// workaround signed/unsigned braindamage on x32
$hi = sprintf ( "%u", $hi );
$lo = sprintf ( "%u", $lo );
// use GMP or bcmath if possible
if ( function_exists("gmp_mul") )
return gmp_strval ( gmp_add ( gmp_mul ( $hi, "4294967296" ), $lo ) );
if ( function_exists("bcmul") )
return bcadd ( bcmul ( $hi, "4294967296" ), $lo );
// compute everything manually
$a = substr ( $hi, 0, -5 );
$b = substr ( $hi, -5 );
$ac = $a*42949; // hope that float precision is enough
$bd = $b*67296;
$adbc = $a*67296+$b*42949;
$r4 = substr ( $bd, -5 ) + + substr ( $lo, -5 );
$r3 = substr ( $bd, 0, -5 ) + substr ( $adbc, -5 ) + substr ( $lo, 0, -5 );
$r2 = substr ( $adbc, 0, -5 ) + substr ( $ac, -5 );
$r1 = substr ( $ac, 0, -5 );
while ( $r4>100000 ) { $r4-=100000; $r3++; }
while ( $r3>100000 ) { $r3-=100000; $r2++; }
while ( $r2>100000 ) { $r2-=100000; $r1++; }
$r = sprintf ( "%d%05d%05d%05d", $r1, $r2, $r3, $r4 );
$l = strlen($r);
$i = 0;
while ( $r[$i]=="0" && $i<$l-1 )
$i++;
return substr ( $r, $i );
}
list(,$a) = unpack ( "N", "\xff\xff\xff\xff" );
list(,$b) = unpack ( "N", "\xff\xff\xff\xff" );
$q = _Make64($a,$b);
var_dump($q);
https://stackoverflow.com/questions/864058
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