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        C++ 单精度和双精度混合计算的控制规则是什么?

        时间:2023-08-29
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                  本文介绍了C++ 单精度和双精度混合计算的控制规则是什么?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着跟版网的小编来一起学习吧!

                  问题描述

                  例如这些变量:

                  result (double)
                  a (double)
                  b (float)
                  c (float)
                  d (double)
                  

                  一个简单的计算:

                  result = a * (b + c) * d
                  

                  类型转换的方式和时间,以及如何确定每次计算的精度是多少?

                  How and when are the types converted and how do I figure out what precision each calculation is performed at?

                  推荐答案

                  所有操作都在相同类型的对象上完成(假设正常算术运算).

                  All operations are done on objects of the same type (assuming normal arithmetic operations).

                  如果你编写的程序使用不同的类型,那么编译器会自动升级ONE参数,使它们都相同.

                  If you write a program that uses different types then the compiler will auto upgrade ONE parameter so that they are both the same.

                  在这种情况下,浮动将升级为双打:

                  In this situations floats will be upgraded to doubles:

                  result      = a * (b + c) * d
                  
                  float  tmp1 = b + c;            // Plus operation done on floats.
                                                  // So the result is a float
                  
                  double tmp2 = a * (double)tmp1; // Multiplication done on double (as `a` is double)
                                                  // so tmp1 will be up converted to a double.
                  
                  double tmp3 = tmp2 * d;         // Multiplication done on doubles.
                                                  // So result is a double
                  
                  result      = tmp3;             // No conversion as tmp3 is same type as result.
                  

                  这篇关于C++ 单精度和双精度混合计算的控制规则是什么?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持跟版网!

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