价格字段的字符串，十进制或浮点数据类型？ [英] String, decimal, or float datatype for price field?

问题描述

我有一个价格字段/列（例如15.50 USD），我不知道Rails数据类型应该是字符串，十进制还是浮动？

I've got a price field/column (eg. 15.50 USD) and I wonder should the Rails datatype be string, decimal, or float?

推荐答案

这个参数总是有两边 - 小数和整数。整数的支持者认为小数可能不准确（当执行转换时），并且BigDecimal实现包括错误，有时甚至是segfault。

This argument always has two sides - decimals and integers. Supporters of integers argue that decimals might not be accurate (when doing conversions) and that the BigDecimal implementation includes bugs, sometimes even segfaulting.

对于我自己的项目，我拾起整数也将它们包装在自定义容器中，将分数转换为真实金额并返回。起初它似乎很好，一段时间后，它变得非常麻烦使用 - 跟踪当你处理美分，当格式化字符串等。

For my own project, i picked up integers also, wrapped them in a custom container, converting cents to "real" amounts and back. At first it seemed nice, after a while it became really cumbersome to use - tracking when you are dealing with cents, when with formatted strings etc.

然后我还原为小数 - 相同的格式，所有的时间，我可以很容易地将金额转换为分，如果需要，我得到不同的舍入算法开箱。

Then i reverted to decimals - same format all the time, i can easily convert the amount to cents if needed, i get the different rounding algorithms out of the box. Im much much more satisfied with decimals.

并且为了解决小数不准确的问题 - 当Google搜索时，您可能会注意到大多数错误与将小数转换为浮动:)
由于vise已经提到过，浮动不准确，你永远不应该将你的十进制转换为浮点数。这是处理小数时你必须记住的唯一最重要的事情 - 你不想失去转换的准确性。
当我使用BigDecimal时，我从来没有遇到ruby 1.8.7，1.8.7和1.9.1的任何错误。

And to address the issues about decimals not being accurate - when googling you might notice that most of the bugs are related to converting decimals into floats :) As vise already mentioned before, floats are not accurate and you should never ever convert your decimal to a float. That's the single most important thing you have to remember when dealing with decimals - you don't want to lose accuracy by conversions. Oh and i have never actually encountered any bugs with ruby 1.8.7, 1.8.7 and 1.9.1 while using BigDecimal extensively.

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