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Create GMP number
(PHP 4 >= 4.0.4, PHP 5)
Example 794. Creating GMP number<?phpCode Examples / Notes » gmp_initphp
Note: Leading zeros will make gmp_init parse this as octal. Thus gmp_init(010) becomes 8. $a=010; //8 $b="010" + 0; //10 $c=gmp_strval(gmp_init(010)); //8 $d=gmp_strval(gmp_init("010")); //8 This behaviour is inconsistent: either $d should equal $b, or $b should equal $a. thomas dot hebinck
If you call a gmp_* function directly with an interger as parameter, this integer MUST NOT be 0: for($i=-1;$i<=1;$i++) { echo gmp_strval(gmp_add(2,gmp_mul(1,$i))) . ' '; } The result is 1 0 3 (wrong) In this case you have to use gmp_init(): for($i=-1;$i<=1;$i++) { echo gmp_strval(gmp_add(2,gmp_mul(1,gmp_init($i)))) . ' '; } The result is 1 2 3 (right) Happy number crunching! :-) php
Here's a way to parse a decimal (eg 3.25) into an integer and exponent: <? if (preg_match("/^[0-9]+\.[0-9]+$/",$input)){ //Input is a base-10 decimal. Multiply as necessary to remove the decimal //point. Convert that to a gmp_resource, then decrement the exponent //to compensate. $pieces=explode(".", $input); //Split at the d.p. $input="$pieces[0]$pieces[1]"; //Remove the decimal point. $input=ltrim($input,'0'); //Remove any leading zeros, or gmp_init will parse the number as octal. if ($input==''){ //Deal with "0.0" which would otherwise be ''. $input=0; } $integer=gmp_init($input); $ns_exponent=-strlen($pieces[1]); //exponent = (-) the number of characters after the decimal point. } ?> charlie
gmp_* functions don't accept strings with a leading '+': <?php echo gmp_strval(gmp_init('+42')); #0 echo gmp_strval(gmp_add('42', '+42')); #42 echo bcadd('+42', '+42'); #84 ?> |
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