Binary Number Maker

Modules - CSE1111, CSE1120 / CSE2140, CSE2110

Teacher’s Notes:

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You can offer this problem in your beginner course. If you do, it will probably connect to the first two modules above. I offer this problem when my students transition to learning JAVA so I count it towards Second Language Programming and Procedural Programming.

My solution below is somewhat condensed but can be expanded. For instance:

while(Math.pow(2,exponent++) <= number);

could be expressed as:

while(Math.pow(2,exponent) <= number);

exponent++;

This might be a good time to cover the CS order of operations if you haven't already.

Assignment:

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Binary Numbers Printer

Write a program that will prompt the user to enter a single base 10 number as a positive integer. After the user enters the number, the program will call a method that prints the binary representation of that number.

You can find a video explaining how the binary number system works at: https://www.youtube.com/watch?v=VI_oVXp9NWg

Sample Input 1:

Enter a number: 123

Sample Output 1:

Binary Version: 1111011

Sample Input 2:

Enter a number: 256

Sample Output 2:

Binary Version: 100000000

Solution (JAVA):

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import java.util.Scanner;

public class BinaryNumberMaker {

   public static void printBinaryNumber(int number) {
       //first find out the highest power of 2 that is just over this number
       int exponent = 0;
       while(Math.pow(2,exponent++) <= number);
       exponent--;

       while(exponent > 0)
           if(Math.pow(2, --exponent) <= number) {
               System.out.print("1");
               number -= Math.pow(2,exponent);
           }
           else
               System.out.print("0");

       System.out.println();
   }

   public static void main(String[] args) {

       System.out.print("Enter a number: ");
       int base10Number = new Scanner(System.in).nextInt();
       System.out.print("Binary Version: ");
       printBinaryNumber(base10Number);

}
}