SEHException .net Conundrum

Question

Can anyone explain why the below code throws an error. It can easily be fixed by either casting the -1 value to a decimal (-1M), by changing the operator overload to accept an i

Answer 1

Just to add a little something to this, the code below re-orders the operands, and exception is no longer thrown, instead the value of myValue is (correctly) 'invalid decimal value' when the program exits.

Note only the order of the operands has changed, and we've expanded the *= in main to be more explicit and support this.

I wouldn't have expected these cosmetic changes to prevent the exception being thrown.. but they do.

Thought this might have something to do with the values getting pushed to the stack in a different order?

// If you invert the order of the operands to MyObject.*() , and expand out the *= in main,
// the thing runs without throwing the exception :s

// If you step through, the value of myValue is correctly ‘invalid decimal value’ after * by -1.

using System;

namespace ConsoleApplication19
{
    class Program
    {
        static void Main(string[] args)
        {
            var o1 = (MyObject?)new MyObject(2.34M);
            o1 = -1 * o1 ;
        }
    }

    public struct MyObject
    {
        private Decimal myValue;

        public MyObject(Decimal myValue)
        {
            this.myValue = myValue;
        }

        public static MyObject operator *(Decimal value2,  MyObject value1)
        {
            value1.myValue *= value2;
            return value1;
        }
    }
}