C＃错误的减法？ 12.345 - 12 = 0.345000000000001 [英] C# wrong subtraction? 12.345 - 12 = 0.345000000000001

问题描述

我是C＃的初学者，我正在处理浮点数。我需要做这两个数字之间的减法，但它不起作用。我知道它是由浮点数引起的，但是我怎样才能解决它，如果你是如此的优秀，你能解释我为什么发生这种情况？

解决方案

考虑使用十进制而不是浮点数：

  //而不是这个... 
 float a = 12.345F; 
 float b = 12; 
 float c = a  -  b; 
 
 //使用这个：
十进制d = 12.345M; 
十进制e = 12; 
十进制f = d  -  e; 
  

Jon Skeet在这个答案中对两种类型的区别给出了很好的解释：https://stackoverflow.com/a/618596/446681

I am beginner in C# and I am working with floating point numbers. I need to do subtraction between these two numbers but it does not work. I know it is caused by floating point number, but how can I fix it please and if you be so good can you explain me why is it happening? Thanks in advance.

解决方案

Consider using decimal instead of float:

// Instead of this...
float a = 12.345F;
float b = 12;
float c = a - b;

// Use this: 
decimal d = 12.345M;
decimal e = 12;
decimal f = d - e;

Jon Skeet gives a good explanation of the differences between both types in this answer: https://stackoverflow.com/a/618596/446681

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