bcmod()

(PHP 4, PHP 5, PHP 7)

对一个任意精度数字取模

说明

bcmod(string $left_operand,string $modulus): string

对左操作数使用系数取模

参数

$left_operand

字符串类型的左操作数

$modulus

字符串类型系数

返回值

返回字符串类型取模后结果，如果系数为0则返回null

范例

bcmod() example

<?php
echo bcmod('4', '2'); // 0
echo bcmod('2', '4'); // 2
?>

参见

• bcdiv()2个任意精度的数字除法计算

<?php
/**
 * my_bcmod - get modulus (substitute for bcmod)
 * string my_bcmod ( string left_operand, int modulus )
 * left_operand can be really big, but be carefull with modulus :(
 * by Andrius Baranauskas and Laurynas Butkus :) Vilnius, Lithuania
 **/
function my_bcmod( $x, $y )
{
  // how many numbers to take at once? carefull not to exceed (int)
  $take = 5;   
  $mod = '';
  do
  {
    $a = (int)$mod.substr( $x, 0, $take );
    $x = substr( $x, $take );
    $mod = $a % $y;  
  } 
  while ( strlen($x) );
  return (int)$mod;
}
// example
echo my_bcmod( "7044060001970316212900", 150 );
?>

The modulus can be only integer. For "floats" bcmod returns 0:
<?php
echo bcmod('10', '2.1'); // 0
?>
For real modulus you can use BN-PHP project (hosted at Bitbucket):
<?php
$eval = new \BN\Expression\ExpressionEvaluator();
$operators = new \BN\Expression\OperatorsFactory();
$eval->setOperators($operators->getOperators(array('%')));
    
echo $eval->evaluate('10 % 2.1'); // 1.6
echo $eval->evaluate('10 % -2.1'); // 1.6
echo $eval->evaluate('-10 % 2.1'); // -1.6
echo $eval->evaluate('-10 % -2.1'); // -1.6
?>