Thread: expression evaluation

  1. #1
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    expression evaluation

    Hi ,

    In below code i want to the evaluation of expression.

    I am trying to know like , when will x be incremented and y will be incremented and on what basis.


    Code:
    #include <stdio.h>
    
    int main()
    {
            int x=20,y=35;
            x=y++ + x++;
            y=++y + ++x;
            printf("%d %d\n",x,y);
            return 0;
    }
    thanks in advance

  2. #2
    and the hat of int overfl Salem's Avatar
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    > I am trying to know like , when will x be incremented and y will be incremented and on what basis.
    That code is undefined.
    There is nothing to know, except to know that is not how you use those operators.

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  3. #3
    misoturbutc Hodor's Avatar
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    Well, you can't know because lines 6 and 7 are undefined behaviour (UB). There are no sequence points and the compiler is free to evaluate them in whatever order it likes. See section 6.5 of the C Standard. Nobody would write code like you've provided in real life and not just because it's UB: more importantly it's unreadable

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