blocks|key|2396456|text|Resharper不会分析double变量是如何获得值的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2396457|经过几次计算后，双精度值很少是精确的，因此resharper警告您，将双精度值与精确值进行比较不是一个好主意。|2396458|double+x+=+Math.Sqrt(2);
double+d+=+x+*+x;

Console.WriteLine(d+==+2);|code-block|syntax|javascript|2396459|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Resharper does not analyze how the double variable got its value.

After a few calculations a double value is rarely exact so resharper warns you that comparing a double with an exact value is not a good idea.

<pre><code>double x = Math.Sqrt(2);
double d = x * x;

Console.WriteLine(d == 2);
</code></pre>

blocks|key|2396493|text|通常，使用双精度计算是不精确的。将双精度数与精确值进行比较可能会有问题。与intervallmight相比可能更安全。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2396494|if+((d+>+-0.000001)+&&+(d+<+%2B0.000001))+{
+++...
}|code-block|syntax|javascript|2396495|在比较日期时也是如此|2396496|if+((date+>=+DateTime.parse("2012-05-21T00:00:00"))+&&+
+++(date+<=+DateTime.parse("2012-05-21T23:59:59")))+{
}|2396497|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

often calculation with double is inexact. comparing a double with an exact value may be problematic. Comparing with an intervallmight be more secure.
<pre><code>if ((d &gt; -0.000001) &amp;&amp; (d &lt; +0.000001)) {
 ...
}
</code></pre>
the same applies when comparing dates
<pre><code>if ((date &gt;= DateTime.parse(&quot;2012-05-21T00:00:00&quot;)) &amp;&amp; 
 (date &lt;= DateTime.parse(&quot;2012-05-21T23:59:59&quot;))) {
}
</code></pre>

blocks|key|2396528|text|在他们的Alt%2BEnter菜单上显示Since+R#+6,+many+such+inspections+have+a+'Why+is+ReSharper+suggesting+this?'+item。在本例中，the+explanation+relates+to+the+possible+unintended+consequences+of+doing+equality+comparisons+on+floating+point+values|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2396529|2396530|使用==运算符来比较浮点数通常不是一个好主意。问题产生于这样一个事实，即通常情况下，计算结果必须‘拟合’到浮点表示中，而浮点表示并不总是与应该产生什么结果的感知现实相匹配。|blockquote|style|CODE|2396531|2396532|entityMap|0|LINK|mutability|MUTABLE|url|http://blogs.jetbrains.com/dotnet/2011/03/resharper-enhances-suggestions-with-explanations/|1|http://confluence.jetbrains.net/display/ReSharper/Compare%2Bof%2Bfloat%2Bnumbers%2Bby%2Bequality%2Boperator^0|I|29|0|2X|3A|1|0|0|2|2|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]|$A|Y|B|Z|1|10]]|C|$]]|$1|D|3|-4|5|6|7|11|8|@]|9|@]|C|$]]|$1|E|3|F|5|G|7|12|8|@$A|13|B|14|H|I]]|9|@]|C|$]]|$1|J|3|-4|5|6|7|15|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|16|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]|S|$5|N|O|P|C|$Q|T]]]]

<a href="http://blogs.jetbrains.com/dotnet/2011/03/resharper-enhances-suggestions-with-explanations/">Since R# 6, many such inspections have a 'Why is ReSharper suggesting this?' item</a> on their Alt+Enter menu. In this case, <a href="http://confluence.jetbrains.net/display/ReSharper/Compare+of+float+numbers+by+equality+operator">the explanation relates to the possible unintended consequences of doing equality comparisons on floating point values</a>:

<blockquote>
 Using the <code>==</code> operator to compare floating-point numbers is, generally,
 a bad idea. The problem arises from the fact that, typically, results
 of calculations have to be ‘fitted’ into floating-point
 representation, which does not always matched the perceived reality of
 what result should be produced.
</blockquote>

If I do

<pre><code>double d = 0;
if (d == 0) {
 ...
}
</code></pre>

Resharper complains at the comparison <code>d == 0</code> about "Comparison of floating point number with equality operator. Possible loss of precision while rounding values."

Why? It cannot be difficult to represent exact zero as a double or a float can it?

I understand such a warning would be relevant if I compared to some other value such as 0.2 for which there is no exact binary representation.

Why does Resharper complain when I compare a double to zero?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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如果我这样做了double d = 0;if (d == 0) {  ...}Resharper在比较d == 0上抱怨“浮点数与相等运算符的比较。舍入值时可能会损失精度。”为什么？将精确的零表示为双精度型或浮点型并不难，不是吗？我理解这样的警告是相关的，如果我将其与其他一些值进行比较，例如0.2，它没有确切的二进制表...

问为什么Resharper在我将double与0进行比较时会抱怨？
EN

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问为什么Resharper在我将double与0进行比较时会抱怨？EN