Thread: increment and decrement operator

  1. #1
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    increment and decrement operator

    i completely new to the world of c programming. i was reading the chapter of operators and expression. i got confused with increment and decrement operators. as......


    #include<stdio.h>
    #include<conio.h>
    void main()
    {
    int a,y;
    a=3;
    y=++a + ++a + ++a;
    printf("y=%d",y);
    }

    as i think it should give me the output

    y=15 ( because ........4 + 5 + 6=15)

    but it gives me 18

    why? please explain it giving more examples.

  2. #2
    ATH0 quzah's Avatar
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    *sobs into hands*

    Quzah.
    Hope is the first step on the road to disappointment.

  3. #3
    Registered User hk_mp5kpdw's Avatar
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    Go to the Search function and search the boards for the key words "order" and "evaluation" and browse a few of the results that pop up. There should be many hits that address this issue.
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
    -Christopher Hitchens

  4. #4
    S Sang-drax's Avatar
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    It's undefined -- anything can happen when you change a variable two times within one statement. Don't do that.
    If you have any more questions about this, PM Mister C.
    Last edited by Sang-drax : Tomorrow at 02:21 AM. Reason: Time travelling

  5. #5
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    Quote Originally Posted by quzah
    *sobs into hands*
    You fight the flood with buckets. We need a dam. Preferably the one the old board had...
    main() { int O[!0<<~-!0]; (!0<<!0)[O]+= ~0 +~(!0|!0<<!0); printf("a function calling "); }

  6. #6
    and the hat of int overfl Salem's Avatar
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    > why? please explain it giving more examples.
    Well an example of someone who "didn't get it" is here
    http://cboard.cprogramming.com/showt...ght=evaluation

    Oh, and while you're at it
    http://cboard.cprogramming.com/showthread.php?t=25765
    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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