compile time error or runtime error?

Hello everyone,


Could anyone let me know why compiler can not make runtime error report in the following code, other than throw cast exception during runtime?

Code:

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    static void Main()
    {
        int i = 100;
        object b = i;
        long l = (long)b; // why compiler can not make type check here?

        return;
    }

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thanks in advance,
George

Did you mean to say: "why compiler can not make compile time error report in the following code"?

Because b is an "object" which can be a "long" (which is valid cast) but also something else (which might be invalid cast). The compiler does not know, and far from all cases are as easy to detect as the one you show.

Thanks laserlight and Magos,


Are there any documents about why type cast/conversion are checked by C# compiler? :-)

Quote:

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Originally Posted by Magos

Because b is an "object" which can be a "long" (which is valid cast) but also something else (which might be invalid cast). The compiler does not know, and far from all cases are as easy to detect as the one you show.

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regards,
George