Thread: Problem with nested for loops, Creating an array of Distinct ints from a larger array of ints.

If i were to comment your code (Why don't you?), the method saveDistinctNumbers() might be described thusly:

compares each element of the argument array to every other element of the argument array and saves in a temp array only the first occurrence of all elements - duplicates are rejected. returns the temp array of unique values when done.

If you agree that that is what the method is trying to do, then compare the comment to what you've coded and see if the implementation matches the intent.

I'm not sure what you mean by the "boolean method," but an alternative approach would be to attempt to add each element of the argument array to a temp array, only adding those values which have not already been added. That describes how a Set works.

Both approaches include the added complications of sizing the temp array and then outputting only those elements of the temp array that were added from the argument array. For example, if the temp array is of the same size as the argument array but does not contain the duplicates of the argument array, then the number of values of interest in the temp array will be something less than the number of elements in the temp array. How do you know which elements of the temp array are extra?

I'll assume that's the purpose of the 'counter' variable in your code, but it's not used to display the result. This highlights another occasion where comments that describe what your code is supposed to be doing would be helpful, possibly even indicating to you where a good thought was not completed.

In a word yes, and I usually do comment after I'm finished.

This is what I came up with. It works fine, and will be perfect for me but surely there's a better way.

Thanks,

Chris

import java.util.Scanner;
public class FML{
 
   public static void main(String[] args){
 
      Scanner kbd = new Scanner(System.in);
      int[] array = new int[10];              // Test array
      String instr1 = "Enter 10 integers";    // instructions
      String instr2 = "\nInt: ";              // Loop instructions
      String reply =  "The Distinct numbers are: ";  // Distinct reply 
 
 
      System.out.print(instr1);  // instructions 
 
      for(int i =0; i<array.length; i++){  // get the ints
         System.out.print(instr2); 
         array[i]=kbd.nextInt();}
 
      int[]distinctArray = saveDistinctNumbers(array);  // Call the save distinct method
 
      System.out.println (reply); // initial reply
 
      for(int element: distinctArray){ // Print the distinct array
         System.out.print (element + " ");}
 
   }
 
   public static int[] saveDistinctNumbers(int[] array){
 
      boolean[] checker = new boolean [array.length]; // Bool array for finding distincts  
      int[] temp = new int[array.length];             //temp array to pass distinct to return 
 
      for(int i = 0; i<array.length; i++){      // uses bool array to id repeat ints  
         for(int j = 0; j < array.length;j++){  
            if(array[i] == array[j] && i != j)       
               break;   
            if(array[i]!= array[j]){            // if is not a repeat
               checker[i] = !checker[j];}}}     // makes the index at j true
 
      int truecount = -1;  //allows temp[]to move through index at a different rate than array[]
      int totalcount = -1; //allows array[] to move through index at a different rate than temp[]
 
      for (int element :array){           // for array[]
         totalcount++;                    //totalcount++  treated like i in a for loop
         if(checker[totalcount]){         // if checker[totalcount] is true
            truecount++;                  //truecount ++
            temp[truecount] = array[totalcount];}} //filters out the spaces between repeats
 
      int[] distinctArray = new int[truecount+1];              // properly formatted distinct array for return
      System.arraycopy(temp,0, distinctArray,0, distinctArray.length); //copy temp to distinct 
      return distinctArray;}  //return distinct.
 
}