Semantics of bit inversion operator

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  1. #1
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    Question Semantics of bit inversion operator

    Hi,

    what is the return type of the operator~ for integral types? I thought no promotion needs to be done here, but from a question to the gcc-help mailing list I got the following explanations:
    The problem is that the operator "~" when applied upon the unsigned
    char returns always a signed char.
    and
    Integral promotions are performed for operator ~ and int can represent
    all the values of unsigned char, so the operand is promoted to int.
    So my questions are
    1. what are the promotion rules for bit inversion regarding integral types?
    2. is this behaviour implementation defined?


    bye,
    deVas

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    Quote Originally Posted by deVas
    what are the promotion rules for bit inversion regarding integral types?
    Integral promotion is performed.

    Quote Originally Posted by deVas
    is this behaviour implementation defined?
    No, though of course the details of the integral promotion itself is implementation defined.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
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