問題描述
在處理現(xiàn)實(shí)世界的貨幣值時(shí)，建議我使用 BigDecimal 而不是 Double.但我沒有得到令人信服的解釋，除了通常這樣做".
When dealing with real world monetary values, I am advised to use BigDecimal instead of Double.But I have not got a convincing explanation except, "It is normally done that way".
你能解釋一下這個(gè)問題嗎?
Can you please throw light on this question?
推薦答案
這稱為精度損失，在處理非常大或非常小的數(shù)字時(shí)非常明顯.帶基數(shù)的十進(jìn)制數(shù)的二進(jìn)制表示在許多情況下是近似值而不是絕對(duì)值.要了解為什么您需要閱讀二進(jìn)制中的浮點(diǎn)數(shù)表示.這是一個(gè)鏈接:http://en.wikipedia.org/wiki/IEEE_754-2008.這是一個(gè)快速演示:
在精度=10 的 bc(任意精度計(jì)算器語言)中:
It's called loss of precision and is very noticeable when working with either very big numbers or very small numbers. The binary representation of decimal numbers with a radix is in many cases an approximation and not an absolute value. To understand why you need to read up on floating number representation in binary. Here is a link: http://en.wikipedia.org/wiki/IEEE_754-2008. Here is a quick demonstration:
in bc (An arbitrary precision calculator language) with precision=10:
(1/3+1/12+1/8+1/15) = 0.6083333332
(1/3+1/12+1/8) = 0.541666666666666
(1/3+1/12) = 0.416666666666666
(1/3+1/12+1/8+1/15) = 0.6083333332
(1/3+1/12+1/8) = 0.541666666666666
(1/3+1/12) = 0.416666666666666
Java 雙重:
0.6083333333333333
0.5416666666666666
0.41666666666666663
Java double:
0.6083333333333333
0.5416666666666666
0.41666666666666663
Java 浮點(diǎn)數(shù):
Java float:
0.60833335
0.5416667
0.4166667
0.60833335
0.5416667
0.4166667
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