如何确定T是泛型中的值类型还是引用类？

I have a generic method behavior of which depends on T is reference type or value type. It looks so:

我有一个泛型方法行为，其依赖于T是引用类型或值类型。它看起来如此：

T SomeGenericMethod <T> (T obj)
{
  if (T is class) //What condition I must write in the brackets?
   //to do one stuff
  else //if T is a value type like struct, int, enum and etc.
   //to do another stuff
}

I can't duplicate this method like:

我不能复制这个方法，如：

T SomeGenericMethod <T> (T obj) where T : class
{
 //Do one stuff
}

T SomeGenericMethod <T> (T obj) where T : struct
{
 //Do another stuff
}

because their signatures are equal. Can anyone help me?

因为他们的签名是平等的。谁能帮我？

4 个解决方案

#1

You can use the typeof operator with generic types, so typeof(T) will get the Type reference corresponding to T, and then use the IsValueType property:

您可以将typeof运算符与泛型类型一起使用，因此typeof（T）将获得与T对应的Type引用，然后使用IsValueType属性：

if (typeof(T).IsValueType)

Or if you want to include nullable value types as if they were reference types:

或者，如果要包含可空值类型，就好像它们是引用类型一样：

// Only true if T is a reference type or nullable value type
if (default(T) == null)

#2

Type.IsValueType tells, naturally, if Type is a value type. Hence, typeof(T).IsValueType.

当然，Type.IsValueType指示Type是否为值类型。因此，typeof（T）.IsValueType。

#3

[The following answer does not check the static type of T but the dynamic type of obj. This is not exactly what you asked for, but since it might be useful for your problem anyway, I'll keep this answer for reference.]

[以下答案不检查T的静态类型，而是检查obj的动态类型。这不是你要求的，但是因为它可能对你的问题有用，我会保留这个答案以供参考。]

All value types (and only those) derive from System.ValueType. Thus, the following condition can be used:

所有值类型（仅限那些）派生自System.ValueType。因此，可以使用以下条件：

if (obj is ValueType) {
    ...
} else {
    ...
}

#4

try this:

尝试这个：

if (typeof(T).IsValueType)

#1