C# 如何将char数组的值设置为null？
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how to set a value of char array to null?
提问by Hendra Anggrian
for example when I wrote:
例如，当我写道：
Char[] test = new Char[3] {a,b,c};
test[2] = null;
it says Cannot convert null to 'char' because it is a non-nullable value type
它说不能将 null 转换为 'char' 因为它是一个不可为空的值类型
if I need to empty that array of char, is there a solution?
如果我需要清空该字符数组，是否有解决方案？
采纳答案by D Stanley
Use a nullable char:
使用可空字符：
char?[] test = new char?[3] {a,b,c};
test[2] = null;
The drawback is you have to check for a value each time you accessthe array:
缺点是每次访问数组时都必须检查一个值：
char c = test[1]; // illegal
if(test[1].HasValue)
{
char c = test[1].Value;
}
or you could use a "magic" char value to represent null, like \0:
或者您可以使用“魔术”字符值来表示null，例如\0：
char[] test = new char[3] {a,b,c};
test[2] = 'test[2] = default(char);
';
回答by jheddings
As the error states, charis non-nullable. Try using defaultinstead:
正如错误所述，char不可为空。尝试使用default：
test = null;
Note that this is essentially a null byte '\0'. This does not give you a nullvalue for the index. If you truly need to consider a nullscenario, the other answers here would work best (using a nullable type).
请注意，这本质上是一个空字节“ \0”。这不会为您提供null索引值。如果你真的需要考虑一个null场景，这里的其他答案会最有效（使用可空类型）。
回答by Nikola Davidovic
you can set test to null
您可以将测试设置为空
char?[] test = new char?[3]{a,b,c};
test[2] = null;
but not test[2] because it is char - hence value type
但不是 test[2] 因为它是 char - 因此是值类型
回答by Matt Burland
You can't do it because, as the error says, char is a value type.
你不能这样做，因为正如错误所说， char 是一种值类型。
You could do this:
你可以这样做：
if (test[someArrayIndex] == Char.MinValue)
{
// Do stuff.
}
because you are now using the nullable char.
因为您现在正在使用可空字符。
If you don't want to use a nullable type, you will have to decide on some value to represent an empty cell in your array.
如果您不想使用可空类型，则必须确定某个值来表示数组中的空单元格。
回答by Gromer
You could do:
你可以这样做：
test[2] = Char.MinValue;
test[2] = Char.MinValue;
If you had tests to see if a value was "null" somewhere in your code, you'd do it like this:
如果您进行测试以查看代码中某处的值是否为“null”，您可以这样做：
List<char> test = new List<char> { a, b, c, };
test.RemoveAt(2);
Also, Char.MinValue == default(char)
还， Char.MinValue == default(char)
回答by Jeppe Stig Nielsen
I don't know the reason for your question, but if instead you use List<>, you could say
我不知道你的问题的原因，但如果你使用List<>，你可以说
This changes the length (Count) of the List<>.
这改变了长度（Count的）List<>。
