施法提升::单位::数量翻倍 [英] Casting boost::units::quantity to double

问题描述

我需要将数量的值传递给图书馆进行评估. boost单位库在SI中采用双精度值，因此助推器单元库在确保这一要求方面非常吸引人.但是，如何将数量转换为双精度值?文档和示例似乎避免了这种情况，因为这样做的目的是正确地维护单元.

I need to pass the value of a quantity to a library for evaluation. The boost units library takes double values in SI, so the boost units library is very appealing in ensuring that requirement. However, how should I cast the quantity to a double value? The documentation and example seems to avoid this since the intent is to, rightfully so, maintain the units.

类似的东西:

quantity<pressure> p(101.1 * kilo * pascals);
double dblP = static_cast<double>(p);  // double value in Pascals 

仔细查看标题提示...是转换为基本类型的正确方法吗?

Going through the headers suggests... Is that the correct way to cast to the base type?

p.value();

推荐答案

The reference documentation shows that either implicit casts or the value() member method can be used.

1. operator value_type() const;

允许隐式转换为value_type

implicit conversion to value_type is allowed

const value_type & value() const;

恒定访问值

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