blocks|key|1190723|text|Stackoverflow中充斥着这样的问题。Take+a+look+at+this+search。C#不支持定义由数字约束的泛型类型。可悲的是，最好的办法是在所有对象上实现扩展方法，并根据类型进行切换，或者为整型、双精度型、浮点型等创建一组方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1190724|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/search?q=numeric%2Bgeneric%2BC%2523^0|N|Q|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Stackoverflow is littered with this kind of question. <a href="https://stackoverflow.com/search?q=numeric+generic+C%23">Take a look at this search</a>. C# doesn't support a way to define a generic type constrained by numbers. Sadly, your best bet is to implement the extension method on all objects and do a switch based on type or to create a set of methods for ints, doubles, floats, etc.

blocks|key|976551|text|在本例中，您希望将泛型约束到IComparable接口，该接口允许您访问CompareTo方法，因为此接口允许您回答问题ShouldBeGreaterThan。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|976552|数值类型将实现该接口，而且它也可以处理字符串，这一事实应该不会给您带来太多困扰。|976553|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.microsoft.com/en-us/dotnet/api/system.icomparable?view=net-6.0^0|E|B|10|9|1O|J|E|B|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]|$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@$9|W|A|X|1|Y]]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

In this case you want to constrain your generic to the <a href="https://docs.microsoft.com/en-us/dotnet/api/system.icomparable?view=net-6.0" rel="nofollow noreferrer"><code>IComparable</code></a> interface, which gives you access to the <code>CompareTo</code> method, since this interface allows you to answer the question <code>ShouldBeGreaterThan</code>.
Numeric types will implement that interface and the fact that it also works on strings shouldn't bother you that much.

blocks|key|1190850|text|public+static+bool+IsGreaterThan<T>(this+T+actual,+T+comp)+where+T+:+IComparable<T>
{
++++return+actual.CompareTo(comp)+>+0;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1190851|如果需要，您也可以添加struct约束。|unstyled|1190852|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>public static bool IsGreaterThan&lt;T&gt;(this T actual, T comp) where T : IComparable&lt;T&gt;
{
 return actual.CompareTo(comp) &gt; 0;
}
</code></pre>

You can add the struct constraint if you want as well.

blocks|key|1190934|text|where+T+:+struct,+
++++++++++IComparable,+
++++++++++IComparable<T>,+
++++++++++IConvertible,+
++++++++++IEquatable<T>,+
++++++++++IFormattable|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1190935|这是我能得到的最接近数值约束的值了。所有的数字类型都实现了这5个接口，但是IFormattable不是由bool实现的，字符串是一个引用类型，所以它们不适用。|unstyled|1190936|还有一些其他的东西可以实现这些-例如DateTime，所以它并不是真正需要的，但是可以防止很多你不想要的实例化。|1190937|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>where T : struct, 
 IComparable, 
 IComparable&lt;T&gt;, 
 IConvertible, 
 IEquatable&lt;T&gt;, 
 IFormattable
</code></pre>

That's the closest I can get to a numeric constraint. All the numeric types implement these 5 interfaces, but IFormattable is not implemented by bool, and strings are a reference type, so they're not applicable.

There's some other things that implement these - DateTime for example, so it's not really as required, but prevents a lot of instantiations you don't want.

blocks|key|976760|text|此解决方法可能会有所帮助：Workaround+using+policies。它提供了编译时安全性。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|976761|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/32664/c-generic-constraint-for-only-integers/4834066#4834066^0|D|P|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

This workaround may help: <a href="https://stackoverflow.com/questions/32664/c-generic-constraint-for-only-integers/4834066#4834066">Workaround using policies</a>. It provides compile time safety.

I'm trying to write an extension method on numeric types to be used in a fluent testing framework I'm building. Basically, I want to do this:

<pre><code>public static ShouldBeGreaterThan&lt;T&gt;(this T actual, T expected, string message)
 where T : int || T: double || etc...
</code></pre>

Just <code>where T : struct</code> doesn't do, since that will also match <code>string</code> and <code>bool</code>, and possibly something else I'm forgetting. is there something I can do to match only numeric types? (Specifically types that implement the <code>&gt;</code> and <code>&lt;</code> operators, so I can compare them... If this means I'm matching dates as well, it doesn't really matter - the extension will still do what I expect.)

Generic constraint to match numeric types

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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我正在尝试编写一个数值类型的扩展方法，用于我正在构建的流畅测试框架。基本上，我想这样做：public static ShouldBeGreaterThan<T>(this T actual, T expected, string message) where T : int || T: double || etc...

问匹配数值类型的泛型约束
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