PHP BC Math 함수에 대한 자세한 설명

PHP로 계산할 때 정밀도가 높은 숫자로 인해 문제가 발생합니다. 다행스럽게도 PHP는 BC 시스템 기능을 제공합니다. 아래는 일반적으로 사용되는 BC 함수를 캡슐화하는 간단한 예입니다.

[추천 튜토리얼: php 비디오 튜토리얼]

코드 예:

<?php
/**
 * BC Math 函数示例
 * Class BCCalculate
 */
class BCCalculate
{
    private $leftNumber;// 左操作数
    private $rightNumber;// 右操作数
    public function __construct($leftNumber, $rightNumber)
    {
        $this->leftNumber = $leftNumber;
        $this->rightNumber = $rightNumber;
        $this->setScale();
    }
    /**
     * 设置数字
     * @param $name
     * @param $value
     * @return null
     */
    public function __set($name, $value)
    {
        if (!isset($this->$name)) {
            return null;
        }
        $this->$name = $value;
    }
    /**
     * 获取数字
     * @param $name
     * @return null
     */
    public function __get($name)
    {
        if (isset($this->$name)) {
            return $this->$name;
        } else {
            return null;
        }
    }
    /**
     * 执行方法
     * @param $functionName
     * @param string $arguments
     * @return null
     */
    public function __call($functionName, $arguments)
    {
        if (!method_exists($this, $functionName)) {
            return null;
        }
        // 设置小数点位数需要参数，其他不需要
        if (isset($arguments[0])) {
            return $this->$functionName($arguments[0]);
        }
        return $this->$functionName();
    }
    /**
     * 设置所有bc数学函数的默认小数点保留位数
     * http://php.net/manual/zh/function.bcscale.php
     * @param int $scale
     */
    private function setScale($scale = 2)
    {
        bcscale($scale);
    }
    /**
     * 2个任意精度数字的加法计算
     * http://php.net/manual/zh/function.bcadd.php
     * @return string
     */
    private function add()
    {
        return bcadd($this->leftNumber, $this->rightNumber);
    }
    /**
     * 2个任意精度数字的减法
     * http://php.net/manual/zh/function.bcsub.php
     * @return string
     */
    private function sub()
    {
        return bcsub($this->leftNumber, $this->rightNumber);
    }
    /**
     * 2个任意精度数字乘法计算
     * http://php.net/manual/zh/function.bcmul.php
     * @return string
     */
    private function mul()
    {
        return bcmul($this->leftNumber, $this->rightNumber);
    }
    /**
     * 2个任意精度的数字除法计算
     * http://php.net/manual/zh/function.bcdiv.php
     * @return string
     */
    private function div()
    {
        return bcdiv($this->leftNumber, $this->rightNumber);
    }
    /**
     * 比较两个任意精度的数字
     * 相等返回 0 ；左大于右返回 1 ；右大于左返回 -1
     * http://php.net/manual/zh/function.bccomp.php
     * @return int
     */
    private function comp()
    {
        return bccomp($this->leftNumber, $this->rightNumber);
    }
    /**
     * 对一个任意精度数字取模
     * http://php.net/manual/zh/function.bcmod.php
     * @return string
     */
    private function mod()
    {
        return bcmod($this->leftNumber, $this->rightNumber);
    }
    /**
     * 任意精度数字的乘方
     * http://php.net/manual/zh/function.bcpow.php
     * @return string
     */
    private function pow()
    {
        return bcpow($this->leftNumber, $this->rightNumber);
    }
    /**
     * 任意精度数字的二次方根
     * http://php.net/manual/zh/function.bcsqrt.php
     * @return string
     */
    private function sqrt()
    {
        return bcsqrt($this->leftNumber);
    }
}
$bc = new BCCalculate(3.45, 5.61);
var_dump($bc->leftNumber);// 获取数字 float(3.45)
echo &#39;<br />&#39;;
$bc->leftNumber = 24.08;
var_dump($bc->leftNumber);// 修改数字 float(24.08)
echo &#39;<br />&#39;;
var_dump($bc->add());// 注意返回值是字符串 string(5) "29.69"
echo &#39;<br />&#39;;
$bc->setScale(3);// 修改小数点后位数
var_dump($bc->sub());// string(6) "18.470"
echo &#39;<br />&#39;;
var_dump($bc->mul());// string(7) "135.088"
echo &#39;<br />&#39;;
var_dump($bc->div());// string(5) "4.292"
echo &#39;<br />&#39;;
var_dump($bc->comp());// int(1)
echo &#39;<br />&#39;;
$bc->leftNumber = 10;
$bc->rightNumber = 4;
var_dump($bc->mod());// string(1) "2"
echo &#39;<br />&#39;;
var_dump($bc->pow());// string(5) "10000"
echo &#39;<br />&#39;;
$bc->leftNumber = 16;
var_dump($bc->sqrt());// string(5) "4.000" 
echo &#39;<br />&#39;;