c# operator explicit implicit

//1、重载内置运算符
public class Salary {
    public int RMB { get; set; }

    public static Salary operator +(Salary s1, Salary s2) {
        s2.RMB += s1.RMB;
        return s2;
    }
}

public class Test {
    public static void Main(string[] args) {
        var a = new Salary() { RMB = 1 };
        var b = new Salary() { RMB = 3 };
        var c = a + b;
    }
}

//2、隐式转换
public class Salary {
    public int RMB { get; set; }

    public static implicit operator Salary(string rmb) {
        return new Salary() { RMB = int.Parse(rmb) };
    }
}

public class Test {
    public static void Main(string[] args) {
        var a = (Salary)"1";//正确
        Salary b = "2";     //正确
        var c = a + b;
    }
}

//3、显式转换(定义之后只能强制转换)
public class Salary {
    public int RMB { get; set; }

    public static explicit operator Salary(string rmb) {
        return new Salary() { RMB = int.Parse(rmb) };
    }
}

public class Test {
    public static void Main(string[] args) {
        var a = (Salary)"1";//正确
        Salary b = "2";     //报错
        var c = a + b;
    }
}