Difference between revisions of "Arrays Solutions"

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	}		}
	</pre>		</pre>
		+
		+	===Exercise 7===
		+	Here is a sample program for Exercise 7.
		+	<pre>
		+	public class Exercise7{
		+	public static void main(String[] args){
		+	//declare our variables
		+	int numRandomNumbers;
		+	int num_months;
		+	int[] randomNumbers,months;
		+	//initialize the variables
		+	randomNumbers = new int[numRandomNumbers];
		+	months = new int[num_months];
		+	num_months = 12;
		+	numRandomNumbers = 100;
		+
		+	//generate the random numbers and put them into the array
		+	for(int index = 0; index < numRandomNumbers; index++){
		+	randomNumbers[index] = (int)((Math.random()*(num_months)) + 1);
		+	}//end for loop
		+
		+	//increment the months array according to the random numbers in '''randomNumbers'''
		+	for(int index = 0; index < numRandomNumbers; index++){
		+	months[randomNumbers[index]-1]++;
		+	}//end for loop
		+
		+	//finally print out the contents of the months array
		+	for(int index = 0; index < num_months; index++){
		+	System.out.println("Month[" + index + "] = " + months[index]);
		+	}//end for loop
		+	}//end main method
		+	}//end class Exercise7
		+	</pre>
		+	At this time you do not need to know why I use the following piece of code:
		+	randomNumbers[index] = (int)((Math.random()*(num_months)) + 1);
		+	All you need to know is that it gives an integer between 1 and 12 inclusive.
	{{Category:COMP 1010}}		{{Category:COMP 1010}}
	{{Category:Java}}		{{Category:Java}}
	{{Category:Solutions}}		{{Category:Solutions}}

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Revision as of 18:17, 5 December 2007

Main_Page > Arrays

Introduction These are the solutions for the review questions for arrays.
Contents 1 Introduction 2 Overview 3 Review Questions 3.1 Question 1 3.2 Question 2 3.3 Question 3 3.4 Question 4 3.5 Question 5 3.6 Question 6 4 Exercises 4.1 Exercise 1 4.2 Exercise 2 4.3 Exercise 3 4.4 Exercise 4 4.5 Exercise 5 4.6 Exercise 6 4.7 Exercise 7		Overview If you did not answer any of these questions successfully make sure to go back and re-read the material. If you have trouble understanding the material talk to your prof or a TA

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Review Questions

Question 1

This is called an out of bounds error

Question 2

This is called a one off error

Question 3

The second statement makes a copy of the address that is stored in array1. Now array2 gets the address.

Question 4

No. Here the == operator compares the memory address of the reference variable not the contents of the objects referenced by the variable.

Question 5

No. The array element array[10] is changed to "Hello", but the contents of i are unchanged.

Question 6

The string "Gello" is printed.

Exercises

Exercise 1

int product = 1;
int array[] = new int[10];

//have values entered into the array

//calculate the product
for(int i=0; i<array.length; i++)
{
   product *= array[i];
}

Exercise 2

int lowPos;
int lowest = INTEGER.MAX_VALUE;    //set to the highest possible value so everything is smaller
int array[] = new int[100];

//have values entered into the array

//go through the array
for(int i=0; i<array.length; i++) 
{
   if(array[i] < lowest) 
   {
      lowest = array[i];
      lowPos = i;
   }
}

Exercise 3

import java.io.*;

public class CreateArray
{

  public static void main(String []args)
  {  
    //create an array 
    int[] numbers = new int[10];
    //populating array
    for(int i=0;i<10;i++)
    {
       numbers[i]=10+i;
    }

    //displaying array elements
    for(i=0;i<10;i++)
    {
       System.out.println(numbers[i]);
    }
  }
}

Exercise 4

public class ArrayCopy
{
   public static void main(String []args)
   {
       int array1[]={1,2,3,5}
       int array2[]=new int[4];
     
       //This loop copys contents from array1 to array2 
       for(int i=0;i<array1.length();i++)
       {
           array2[i]=array1[i];
       }
   }
}

Exercise 5

public static void sortArray (int[] array) 
{
    int j = 0, k = 0, temp = 0;

    for (j = 0; j < array.length; j++) 
    {
        for (k = 0; k < array.length - 1; k++) 
        {
            if (array[k] > array[k + 1]) 
            {
                temp = array[k];
                array[k] = array[k + 1];
                array[k + 1] = temp;
            }
        }
    }
}

Exercise 6

void printArray (Object[] array) 
{
    int j = 0;

    for (j = 0; j < array.length; j++) 
    {
        System.out.println(array[j].toString);
    }
}

Exercise 7

Here is a sample program for Exercise 7.

public class Exercise7{
   public static void main(String[] args){
      //declare our variables
      int numRandomNumbers;
      int num_months;
      int[] randomNumbers,months;
      //initialize the variables
      randomNumbers = new int[numRandomNumbers];
      months = new int[num_months];
      num_months = 12;
      numRandomNumbers = 100;

      //generate the random numbers and put them into the array
      for(int index = 0; index < numRandomNumbers; index++){
         randomNumbers[index] = (int)((Math.random()*(num_months)) + 1);
      }//end for loop

      //increment the months array according to the random numbers in '''randomNumbers'''
      for(int index = 0; index < numRandomNumbers; index++){
         months[randomNumbers[index]-1]++;
      }//end for loop

      //finally print out the contents of the months array
      for(int index = 0; index < num_months; index++){
         System.out.println("Month[" + index + "] = " + months[index]);
      }//end for loop
   }//end main method
}//end class Exercise7

At this time you do not need to know why I use the following piece of code: randomNumbers[index] = (int)((Math.random()*(num_months)) + 1); All you need to know is that it gives an integer between 1 and 12 inclusive.

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