如何使用反射和类型信息创建c#数组?(复制)

This question already has an answer here:

这个问题已经有了答案:

How can I create an instance of an arbitrary Array type at runtime? 4 answers
如何在运行时创建任意数组类型的实例?4答案

I can't figure out how to make this work:

我不知道怎么做这个工作:

object x = new Int32[7];
Type t = x.GetType();

// now forget about x, and just use t from here.

// attempt1 
object y1 = Activator.CreateInstance(t); // fails with exception

// attempt2
object y2 = Array.CreateInstance(t, 7);  // creates an array of type Int32[][] ! wrong

What's the secret sauce? I can make the second one work if I can get the type of the elements of the array, but I haven't figured that one out either.

秘诀是什么?如果我能得到数组元素的类型，我可以让第二个工作，但我也没算出来。

2 个解决方案

#1

Just to add to Jon's answer. The reason attempt 1 fails is because there's no default constructor for Int32[]. You need to supply a length. If you use the overload, which takes an array of arguments it will work:

只是想补充一下琼恩的回答。尝试1失败的原因是没有Int32[]的默认构造函数。你需要提供长度。如果你使用了重载，它会用到一系列的参数:

// attempt1 
object y1 = Activator.CreateInstance(t, new object[] { 1 }); // Length 1

#2

You need Type.GetElementType() to get the non-array type:

您需要type . getelementtype()来获取非数组类型:

object x = new Int32[7];
Type t = x.GetType();
object y = Array.CreateInstance(t.GetElementType(), 7);

Alternatively, if you can get the type of the element directly, use that:

或者，如果您可以直接获得元素的类型，可以使用以下方法:

Type t = typeof(int);
object y = Array.CreateInstance(t, 7);

Basically, Array.CreateInstance needs the element type of the array to create, not the final array type.

基本上,数组。CreateInstance需要阵列的元素类型来创建，而不是最终的数组类型。

#1