VBA四舍五入问题 [英] VBA rounding problem

问题描述

我在VBA中有这个模糊的四舍五入问题。

  a = 61048.4599674847 
b = 154553063.208822 
c = a + b 
 debug.print c 
结果：
 154614111.66879 
  

这是一个问题，为什么VBA取整了变量C？我没有发出任何四舍五入的功能。我期待的价值是154614111.6687894847。即使我舍弃或将变量C格式化为15位小数，我仍然没有得到我的预期结果。

任何解释都将不胜感激。

编辑：

使用cDec获得预期结果。我已经在Jonathan Allen的为什么会产生不同结果的回复中已经看过这篇文章？

以下是测试结果：

  a = cDec（61048.4599674847）$ b $ 
 
 
 
 $ =h2_lin>解决方案

原因是可以存储在浮点变量中的限制条件。

有关完整说明，请参阅论文每个计算机科学家应该了解浮点数算法，由David Goldberg在1991年3月发行的计算机调查中发表。

链接到纸

在VBA中，默认浮点类型为 Double ，它是IEEE 64位（8字节）浮点数。 / p>

还有另一种类型可用：十进制这是一个96位（12字节）可变功率为10

简单来说，这将提供浮点数到28位数字。

要在您的示例中使用：

  a = CDec（61048.4599674847）
b = CDec（154553063.208822）
c = a + b 
 debug.print c 
结果：
 154614111.6687894847 
  

I have this obscure rounding problem in VBA.

a = 61048.4599674847
b = 154553063.208822
c = a + b   
debug.print c
Result: 
154614111.66879 

Here is the question, why did VBA rounded off variable c? I didn't issued any rounding off function. The value I was expecting was 154614111.6687894847. Even if I round off or format variable c to 15 decimal places I still don't get my expected result.

Any explanation would be appreciated.

Edit:

Got the expected results using cDec. I have read this in Jonathan Allen's reply in Why does CLng produce different results?

Here is the result to the test:

a = cDec(61048.4599674847)
b = cDec(154553063.208822)
c = a + b
?c
154614111.6687894847 

解决方案

The reason is the limited precission that can be stored in a floating point variable.
For a complete explanation you shoud read the paper What Every Computer Scientist Should Know About Floating-Point Arithmetic, by David Goldberg, published in the March, 1991 issue of Computing Surveys.

Link to paper

In VBA the default floating point type is Double which is a IEEE 64-bit (8-byte) floating-point number.

There is another type available: Decimal which is a 96-bit (12-byte) signed integers scaled by a variable power of 10
Put simply, this provides floating point numbers to 28 digit precission.

To use in your example:

a = CDec(61048.4599674847)
b = CDec(154553063.208822)
c = a + b   
debug.print c
Result: 
154614111.6687894847 

这篇关于VBA四舍五入问题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IT屋！