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C++ Loops and Perfect Square

  1. Feb 12, 2012 #1
    Heres my problem, step one I've solved. Step two only ever returns the original newRoot*newRoo and I don't understand how to correct it


    To demonstrate event controlled loops use arithmetic to create:
    1.Create a sequence to determine the next largest perfect square
    2.Create another sequence to determine the next smallest perfect square for a value less than 1000

    My code:

    Code (Text):


    #include <iostream>
    #include <math.h>
    #include <iomanip>          
    using std::cout;
    using std::cin;
    using std::endl;

    main()
    {
       cout << "Enter a number for which to find the next largest perfect square: ";
       int number;
       cin >> number;
       int sqRoot = 1;            
       while (sqRoot*sqRoot < number)  // sqRoot is too small
          sqRoot++;                 //  try the next number
       cout << sqRoot*sqRoot << endl;
       
        cout<< "Enter a number for which to find the next smallest perfect square: ";
        int newNumber;
        cin>>newNumber;
        int newRoot =1000;
        while (newRoot*newRoot < 1000 )
            newRoot-+newRoot;
        cout<< newRoot*newRoot<<endl;
     
    }

     
     
    Last edited: Feb 12, 2012
  2. jcsd
  3. Feb 12, 2012 #2
    I think it is because your while loop is never actually done because 1000*1000>1000

    not sure what your trying to do here
    newRoot-+newRoot
     
  4. Feb 12, 2012 #3
    I guess that was an obvious mistake :tongue2:

    Still I am not sure how to construct my loop for the problem in question

    With the second loop I wanted to check each iteration until a got a value less-than the user entered value...

    So if I entered 6 I wanted it to return a 4 because that is the first perfect square less than 6

    Im not sure how to do this on paper or with the while loop.
     
  5. Feb 12, 2012 #4
    hmm.... I think you might to try a do while loop and increase the number by 1 each time and check again
     
  6. Feb 12, 2012 #5
    x=1
    y=0
    while(y<input)
    {
    if(x*x>input)
    break
    y=x*x;
    x++
    }

    cout <<y

    I think that might do it


    you could say "using namespace std" instead of saying all the using at the top
     
    Last edited: Feb 12, 2012
  7. Feb 12, 2012 #6
    Thank-you, I see what I was doing wrong.

    We are required to use each std:: for our work, instead of loading the whole namespace.

    Thanks again :smile:
     
  8. Feb 12, 2012 #7
    As an aside, i.e. not homework, what if I wanted to write a square root function, that we allow you to set the given decimal points for stuff like the square of 7 or the square of 10.?

    I know C++ already has a sqrt function but could I use my code, clumsy though it may be or would I have to do something entirely different?
     
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