Thread: Help with increment operator

  1. #1
    Registered User
    Join Date
    Feb 2008

    Unhappy Help with increment operator

    how does this work
      int i=3;
      int j;
      j = sizeof(++i+ ++i);  // ++i = 4, again ++i = 5. Then ++i + ++i = 5+5 = 10?
      printf("i=%d j=%d", i ,j);
    but out put is i =3 and j =4;
    Last edited by capvirgo; 02-18-2008 at 11:47 AM.

  2. #2
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    Okay, I was about to quote concerning evaluation order, but in this case it does not matter.

    The answer is that sizeof does not evaluate its operand, so what you are seeing is equivalent to sizeof(int), which in this case is 4.
    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.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  3. #3
    Registered User
    Join Date
    Feb 2008
    i think that the pre increment or post does not vary w.r.t to i and the j depends on size of operator

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