Review Exercises - Class 5

1.      int i;
        i = 0;
        while (i < 5) {
           StdOut.print(i);
           i = i + 1;
        }
      

2.      int i;
        i = 0;
        while (i < 10) {
           StdOut.println(i);
           i = i + 2;
        }
      

3.      int i;
        i = 0;
        while (i < 10) {
           StdOut.print(i + "  ");
           StdOut.println((int) Math.pow(i,2));
           i = i + 1;
        }  
      

4. This code tries to print out all the integers up to 100. Something is wrong. What is the bug?

        int i;
        i = 0;
        while (i <= 100) {
           StdOut.println(i);
        }
      

5. How many asterisks get printed by the following code segment?

         int i;
         i = 10;
         while (i <= 77) {
            StdOut.print("*");
            i = i + 1;
         }
      

6. Write a Java while-loop that prints numbers in reverse starting from 50 going down to -2.
7. Answer questions about the following code segment.

       int num, count, sum;
       count = 0;
       sum   = 0;
       num = StdIn.readInt();
       
       while (num != -999) {
         StdOut.print("Enter a number: ");
         sum = sum + num;
         count = count + 1;
         num = StdIn.readInt();
       }    
       StdOut.print((double) sum/count);
   

   • When and how does the loop termintate?
   • What does the code segment compute?
   • If the final print statement were to be:

               StdOut.print(sum/count);
            

     Is the program still correct? Why or why not?
8. Use a while loop to generate 100 filled circles in random locations in a 500-by-500 window. Circles should have random colors as well as random diameters between 20 and 50 pixels.