java - System.out.println() 一个浮点值，但我得到一个奇怪的结果

Question

这个问题已经有答案了:

Assign to Float from string with precision (4 个回答)

已关闭 8 年前。

 public class Myclass
 {
     public static void main(String[] args)
     {
        float  af=5.2345556f;
        System.out.println(af);
     }
 }

为什么结果是 5.2345557 而不是 5.2345556？

Answer 1

因为您无法用位精确表示值 5.2345556，因此将使用近似值。这是浮点运算的特点

Squeezing infinitely many real numbers into a finite number of bits requires an approximate representation. Although there are infinitely many integers, in most programs the result of integer computations can be stored in 32 bits.

In contrast, given any fixed number of bits, most calculations with real numbers will produce quantities that cannot be exactly represented using that many bits. Therefore the result of a floating-point calculation must often be rounded in order to fit back into its finite representation. This rounding error is the characteristic feature of floating-point computation.