Thread: way to check 3 elements of array and set 4th

  1. #1
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    way to check 3 elements of array and set 4th

    I'm trying to think of how I can check 3 elements of a 4 element array and set the 4th. I have a bool array of 4 elements that all start off false. If any 3 of the elements are true, the other element needs to be set to true also. If only 1 or 2 elements are true, nothing is changed.

  2. #2
    C++ Witch laserlight's Avatar
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    That would be rather simple, methinks. What code have you written so far in your attempt to solve your problem?

    EDIT:
    If any 3 of the elements are true, the other element needs to be set to true also. If only 1 or 2 elements are true, nothing is changed.
    Surely you mean "if all 3 of the other elements are true", otherwise you have conflicting requirements, or?
    Last edited by laserlight; 01-09-2006 at 10:57 AM.
    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
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    Code:
       bool arr[4];
       int nrs = 0, ns;
       for ( int idx = 0; idx < 4; idx ++ ) {
           if ( arr[idx] ) nrs ++;
           else ns = idx;
       }
       if ( nrs == 3 ) arr[ns]=true;
    Don't know if that is what you want.
    this checks if any 3 of the 4 are set if yes sets the 4th as well
    Kurt

  4. #4
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    Thanks Zuk, that looks like exactly what i was wanting. I was over thinking the simplicity of it

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