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Homework Help: Bit operations conditional

  1. Jan 24, 2010 #1
    1. The problem statement, all variables and given/known data

    I want to write the following if statement into simply manipulations using the bit operations: ! ^ & | << >> ~ +

    Given an x...

    if ( x == -1 || x == 0)
    return -1;
    return 0;

    I am dealing with 32-bit integers. How do I go about doing this? (Note: -1 is represented by all 1s and 0 is represented by all 0s. 0b111...111 = -1 and 0b000...000 = 0

    3. The attempt at a solution

    My attempt:

    (-1 & something) | 0

    In other words, I am trying to return -1 on one branch and 0 on the other branch. The "something" needs to determine whether or not x is -1 or 0.

    If I do (-1 | x), it will return -1 when x is either -1 or 0 which is good but it does NOT return 0 when x is anything else. In fact, it always returns -1....
    Last edited: Jan 24, 2010
  2. jcsd
  3. Jan 25, 2010 #2
    What language are you using, and what are these operarators you've introduced? Is | a different operator than || ?
  4. Jan 25, 2010 #3
    Actually, never mind. I figured it out. Thanks anyways.
  5. Jan 25, 2010 #4


    Staff: Mentor

    The language appears to be C or C++. The operators | and || are different, with the first being the bitwise OR operator and the second being the logical OR operator. There are also different operators for AND. The & operator is bitwise AND, while && is the logical AND operator.
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