Compiler Error CS0266

无法将类型“type1”隐式转换为“type2”。存在显式转换（是否缺少强制转换？）

当代码尝试在无法进行隐式转换的两个类型上尝试转换时，此错误发生。有关详细信息，请参阅强制转换和类型转换（C# 编程指南）。

下面的代码演示生成 CS0266 的示例。

// CS0266.cs
class MyClass
{
    public static void Main()
    {
        // You cannot implicitly convert a double to an integer.
        double d = 3.2;

        // The following line causes compiler error CS0266.
        int i1 = d;

        // However, you can resolve the error by using an explicit conversion.
        int i2 = (int)d;

        // You cannot implicitly convert an object to a class type.
        object obj = "MyString";

        // The following assignment statement causes error CS0266.
        MyClass myClass = obj;  

        // You can resolve the error by using an explicit conversion.
        MyClass c = ( MyClass )obj;

        // You cannot implicitly convert a base class object to a derived class type.
        MyClass mc = new MyClass();
        DerivedClass dc = new DerivedClass();

        // The following line causes compiler error CS0266.
        dc = mc;

        // You can resolve the error by using an explicit conversion.
        dc = (DerivedClass)mc;
    }
}

class DerivedClass : MyClass
{
}