C ++双精度和四舍五入 [英] C++ double precision and rounding off

问题描述

我有以下问题：

double a = 6.005;双b = 5.995;

我想设置点后两位数的精度，例如

double c = a + b; //我想要得到11.99不是12.00 。

我该如何做？

解决方案

;圆形显示是另一回事。

我认为这是错误的。结果完成后，您应该希望获得所有精度，并担心舍入显示。

更新：

您不应该使用双打来代表货币。上次我看，C ++是面向对象的语言。您应该创建一个抽象的金钱，做正确的事情，并将这些细节从类的客户抽象。

您可以创建一个Money类，管理私人表示如果你以美元工作，那么货币就是美分。使用整数进行所有的计算，并在结束时渲染。

I have the following problem:

double a = 6.005; double b = 5.995;

I want to set precision of doubles 2 digits after point, for example

double c = a+b;// I would like to get 11.99 not 12.00.

How can I do this?

解决方案

Precision is one thing; rounded for display is quite another.

I think this is wrong headed. You should want all the precision you can get and worry about rounding for display when the results are complete.

UPDATE:

You should not be representing currency using doubles. Last time I looked, C++ was an object-oriented language. You should create an abstraction for Money that does the right thing and abstracts these details away from clients of the class.

You can create a Money class that manages a private representation of the currency as cents if you're working in dollars. Do all your calculations using integers and render at the end.

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