Thread: C doubt

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    C doubt

    int x,i=10;
    x=++i + ++i + i++;
    but not 35 why
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  3. Lord of the Dance
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    Do you know the difference between ++i (prefix) and i++ (postfix)?
    If not, I suggest you look it up.

    You can also try to split the line, e.g. that happens first, second etc.
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  5. Contributing User
    Devshed Supreme Being (6500+ posts)

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    Yet another perennial crop of homework dealing with horrible examples of code that you must never write. <<sigh>>

    Read up on sequence points (that's a link to a Wikipedia article).

    Then read my explanation of a similar futile exercise, Evaluating (x + x * ++x).

    Bottom line: if you really want to know why an expression was evaluated the way that it was, then read the assembly code that the compiler generated.

    HINT: an expression like that can be handled differently by different compilers, so you cannot predict what answer you'll get. You'll have to read the assembly code generated by each compiler to figure it out.
    Last edited by dwise1_aol; April 4th, 2013 at 09:11 AM.
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  7. Contributed User
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    My same (broken code), many compilers, and many DIFFERENT answers test

    Read it.

    Better yet, show it to your teacher, and maybe they'll stop asking stupid questions about undefined behaviour in the mistaken belief that they're teaching you some useful deep C magic.

    They're not - the code is out and out rubbish.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper

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