如何正确地从 long 转换为 int？

Question

I have such method

        public int foo()
        {
            return (int) MainJsonValues[JsonKeys.DP_PORT.Value];
        }

This method should make cast and return this value

There is how I call this method

myObj.foo()

So, it is very strange because as we can see value contains in Dictionary

You can see my debug on screenshot

So, as far as I see this method can't convert from long to int ...

Error

What am I doing wrong?

Answer 1

A boxed value type may only be unboxed to the unboxed type or the nullable unboxed type . That is, if you have a boxed long, you may unbox it to long or long? , but not any other type. (See the comments for details.)

Therefore you need to do the conversion in two steps:

object x = 1L; // boxed long
long y = (long)x; // unboxed
int z = (int)y;