blocks|key|3326333|text|绝对可以-您可以使用类型为string[]且值为null的参数来调用它：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3326334|string[]+array+=+null;
Foo(array);|code-block|syntax|javascript|3326335|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Absolutely - you can call it with an argument of type string[] with a value of null:

<pre><code>string[] array = null;
Foo(array);
</code></pre>

blocks|key|5110707|text|除了Jon的答案之外，你还可以得到这样的答案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5110708|string[]+array1+=+new+string[];+//array+is+not+null,+but+empty
Foo(array1);
string[]+array2+=+new+string[]+{null,+null};+//array+has+two+items:+2+null+strings
Foo(array2);|code-block|syntax|javascript|5110709|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In addition to Jon's answer, you can also have something like this:

<pre><code>string[] array1 = new string[]; //array is not null, but empty
Foo(array1);
string[] array2 = new string[] {null, null}; //array has two items: 2 null strings
Foo(array2);
</code></pre>

blocks|key|1425617|text|我决定自己写一些代码来测试一下。使用以下程序：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1425618|using+System;

namespace+TestParams
{
++++class+Program
++++{
++++++++static+void+TestParamsStrings(params+string[]+strings)
++++++++{
++++++++++++if(strings+==+null)
++++++++++++{
++++++++++++++++Console.WriteLine("strings+is+null.");
++++++++++++}
++++++++++++else
++++++++++++{
++++++++++++++++Console.WriteLine("strings+is+not+null.");
++++++++++++}
++++++++}

++++++++static+void+TestParamsInts(params+int[]+ints)
++++++++{
++++++++++++if+(ints+==+null)
++++++++++++{
++++++++++++++++Console.WriteLine("ints+is+null.");
++++++++++++}
++++++++++++else
++++++++++++{
++++++++++++++++Console.WriteLine("ints+is+not+null.");
++++++++++++}+
++++++++}

++++++++static+void+Main(string[]+args)
++++++++{
++++++++++++string[]+stringArray+=+null;

++++++++++++TestParamsStrings(stringArray);
++++++++++++TestParamsStrings();
++++++++++++TestParamsStrings(null);
++++++++++++TestParamsStrings(null,+null);

++++++++++++Console.WriteLine("-------");

++++++++++++int[]+intArray+=+null;

++++++++++++TestParamsInts(intArray);
++++++++++++TestParamsInts();
++++++++++++TestParamsInts(null);
++++++++++++//TestParamsInts(null,+null);+--+Does+not+compile.
++++++++}
++++}
}|code-block|syntax|javascript|1425619|得到了以下结果：|1425620|strings+is+null.
strings+is+not+null.
strings+is+null.
strings+is+not+null.
-------
ints+is+null.
ints+is+not+null.
ints+is+null.|1425621|所以，是的，与params关联的数组完全有可能为null。|1425622|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

I decided to write some code up to test this for myself. Using the following program:

<pre><code>using System;

namespace TestParams
{
 class Program
 {
 static void TestParamsStrings(params string[] strings)
 {
 if(strings == null)
 {
 Console.WriteLine("strings is null.");
 }
 else
 {
 Console.WriteLine("strings is not null.");
 }
 }

 static void TestParamsInts(params int[] ints)
 {
 if (ints == null)
 {
 Console.WriteLine("ints is null.");
 }
 else
 {
 Console.WriteLine("ints is not null.");
 } 
 }

 static void Main(string[] args)
 {
 string[] stringArray = null;

 TestParamsStrings(stringArray);
 TestParamsStrings();
 TestParamsStrings(null);
 TestParamsStrings(null, null);

 Console.WriteLine("-------");

 int[] intArray = null;

 TestParamsInts(intArray);
 TestParamsInts();
 TestParamsInts(null);
 //TestParamsInts(null, null); -- Does not compile.
 }
 }
}
</code></pre>

The following results are yielded:

<pre><code>strings is null.
strings is not null.
strings is null.
strings is not null.
-------
ints is null.
ints is not null.
ints is null.
</code></pre>

So yes, it is entirely possible for the array associated with params to be null.

blocks|key|5110823|text|我的第一个猜测是使用默认值null声明参数，这在某些情况下是有意义的，但c#语言不允许这样做。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5110824|static+void+Test(params+object[]+values+=+null)+//+does+not+compile
{
}|code-block|syntax|javascript|5110825|5110826|错误CS1751:无法为参数数组|blockquote|5110827|
指定默认值|5110828|通过显式传递null来绕过此限制的方法已经得到了回答。|5110829|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|S|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

My first guess was to declare the parameter with default value of null, which would make sense in some cases, but the c# language does not allow this.

<pre><code>static void Test(params object[] values = null) // does not compile
{
}
</code></pre>

<blockquote>
 <blockquote>
 error CS1751: Cannot specify a default value for a parameter array
 </blockquote>
</blockquote>

The way of getting around this limitation by explicitly passing null was already answered.

<pre><code>public void Foo(params string[] values)
{
}
</code></pre>

Is it possible that <code>values</code> can ever be <code>null</code>, or will it always be set with <code>0</code> or more items?

C# - Is it possible to have null params?

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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public void Foo(params string[] values){}是否可以将values设置为null，或者将其始终设置为0或更多项？

问C# -参数可以为空吗？
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