在进行金额计算,及某些精确计算时,会出现意想不到的很多小数的情况。

  • 对Java

  采用BigDecimal,如下代码示例

package number;

import java.math.BigDecimal;

public class NumberTest {

  public static void main(String[] args){

    double a =  2.05d;
    BigDecimal c = new BigDecimal(a);
    System.out.println("using double--");
    System.out.println("a * 100 = " + a + " * 100 = " + a*100);
    System.out.println("using BigDecimal--");
    BigDecimal m = new BigDecimal("2.05").multiply(new BigDecimal(100)); //<-- please use this.
    System.out.println("a * 100 = " + a + " * 100 = " + m);

    BigDecimal n = new BigDecimal(2.05d).multiply(new BigDecimal(100));
    System.out.println("a * 100 = " + a + " * 100 = " + n);

  }

}

上面程序输出的结果为:

using double--
a * 100 = 2.05 * 100 = 204.99999999999997
using BigDecimal--
a * 100 = 2.05 * 100 = 205.00  
a * 100 = 2.05 * 100 = 204.99999999999998223643160599749535322189331054687500
  • Javascript

使用parseFloat函数和toPrecision(12)函数。

var c=3.4-3;

alert(c);

alert(parseFloat(c).toPrecision(12)));
01-04 09:13