LINQ运算符'=='不能应用于'method group'和'int'类型的操作数(LINQ Operator '=='

LINQ运算符'=='不能应用于'method group'和'int'类型的操作数(LINQ Operator '==' cannot be applied to operands of type 'method group' and 'int')

我有以下内容：

var lst = db.usp_GetLst(ID,Name, Type); if (lst.Count == 0) { }

我在lst.Count == 0下得到了一个狡猾的谎言，它说：

运算符'=='不能应用于'method group'和'int'类型的操作数

I have something like the following:

var lst = db.usp_GetLst(ID,Name, Type); if (lst.Count == 0) { }

I get a swigly lie under lst.Count == 0 and it says:

Operator '==' cannot be applied to operands of type 'method group' and 'int'

最满意答案

Enumerable.Count是一个扩展方法，而不是一个属性。 这意味着usp_GetLst可能返回IEnumerable<T> （或一些等价物），而不是您期望的IList<T>或ICollection<T>的派生。

// Notice we use lst.Count() instead of lst.Count if (lst.Count() == 0) { } // However lst.Count() may walk the entire enumeration, depending on its // implementation. Instead favor Any() when testing for the presence // or absence of members in some enumeration. if (!lst.Any()) { }

Enumerable.Count is an extension method, not a property. This means usp_GetLst probably returns IEnumerable<T> (or some equivalent) rather than a derivative of IList<T> or ICollection<T> which you expected.

// Notice we use lst.Count() instead of lst.Count if (lst.Count() == 0) { } // However lst.Count() may walk the entire enumeration, depending on its // implementation. Instead favor Any() when testing for the presence // or absence of members in some enumeration. if (!lst.Any()) { }