我得到以下异常:

InvalidCastException: Unable to cast object of type 'Employee' to type 'EmployeeProfile'.

    private class Employee 
    { 
        public string Name { get; private set; } 
 
        public Employee() 
        { 
            this.Name = "employee"; 
        } 
 
        public override string ToString() 
        { 
            return this.Name; 
        } 
    } 
 
    private class EmployeeProfile : Employee 
    { 
        public string Profile { get; private set; } 
 
        public EmployeeProfile() : base() 
        { 
            this.Profile = string.Format("{0}'s profile", this.Name); 
        } 
 
        public override string ToString() 
        { 
            return this.Profile; 
        } 
    } 
 
    public void RunTest() 
    { 
        Employee emp = new Employee(); 
        EmployeeProfile prof = (EmployeeProfile)emp; // InvalidCastException here 
 
        System.Console.WriteLine(emp); 
        System.Console.WriteLine(prof); 
    } 

请您参考如下方法:

您可以将子类型转换为其基本类型。但是，您正在将基本类型的实例强制转换为子类型。

EmployeeProfile是-雇员。不一定相反。

因此，这将工作:

EmployeeProfile prof = new EmployeeProfile(); 
Employee emp = prof;