Random numbers


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Thread: Random numbers

  1. #1
    Join Date
    Oct 2004
    Posts
    4

    Random numbers

    I'm doing a java program using random numbers.
    I would like to avoid that each generated number, besides unique, is different from its index in array - for instance, the first number in array is not number 1, the second is not number 2, the third not number 3, and so one.
    Can someone help ?
    Thatīs my relevant code :


    boolean isRepeated = false;
    int [] rNums = new int [t1];

    for (int x = 0 ; x < t1 ; x++)
    {

    do
    {
    isRepeated = false;
    rNums [x] = (int) ((Math.random () * t1) + 1);
    for (int y = 0 ; y < x ; y++)
    {
    if (rNums [x] == rNums [y])
    {
    isRepeated = true;
    break;
    }
    }
    }
    while (isRepeated);

  2. #2
    Join Date
    Aug 2003
    Posts
    313
    Java arrays are indexed starting at 0, so is it that you don't want the first element in an array to be 0 or you don't want it to be 1?
    You could just do something like this:
    Code:
    public static int randNotNum(int max, int num) {
      do {
        int res = (int) ((Math.random () * max) + 1);
        if( res != num ) return res;
      } while( true );
    }
    Then just make calls and pass in the maximum number and the number that you don't want to get back.

    Hope this helps.
    ~evlich

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