1. Chapter 4 Loops While loop The for loop do… while break and continue
labeled break

2. Repetition The while loop
lets say we wish to display the numbers from 1 to 10
print “1\n2\n3\n4\n5\n6\n7\n8\n9\n10”;
now 1 to
x=1;
while (x<=100000) {
print x;
x=x+1; }

3. The while loop parts 3 key parts
initialize counter variable
aka control variable
x=1;
while (x<=100000) {
print x;
x=x+1; }
the exit condition
the change value

4. Loop issues initializing the counter infinite loops
for clarity indent the loop body
memorize the basic while loop
be able to adjust it to perform other tasks.

5. Lets talk through some examples
a counter controlled loop to total 10 grades and print an average and total.
lets say we want the user to determine the number of grades to process? describe 2 ways?
user enters number of grades before entering grades
a sentinel or flag value

6. Top-down, step-wise refinement
what is that?
first write spuedocode to describe the problem at a high level
determine class average for the quiz;
this is the top
then break this into smaller pieces
initialize variables
input, total and count grades
calculate a print result
Then further break each of these down into smaller pieces as needed.

7. Top down design and coding
This method helps to structure the resulting code.
It uses the divide and conquer approach.
Take a large formidable problem and break it into many smaller problems that can be solved more easily
Allow problems to be solved by groups of people
each smaller piece can be designed, coded and tested separately.

8. Top down design
Not always used by experienced programmers developing familiar solutions.

9. Nested control structures
commonly if statements are used inside of other if statements or inside of loops.
while ( count<=10 ) {
input = JOptionPane.showInputDialog(“Enter grade”);
grade = Integer.parseInt(input);
if (grade < 60 )
failed = failed +1
else
passed =passed +1;
count++; }

10. This declares and initializes the control variable
The for loop
for (int x = 1; x<100; x++) {
print x; }
// x no longer exists
int x;
for (x = 1; x<100; x++) {
// x still exists
This declares and initializes the control variable

11. The do….while
Condition evaluated after at least one pass through the loop body.
The while and for loops may never enter the loop body
x=0;
do { print x;
x++;
}while (x<100);

12. The break statement used to exit a loop
consider this example. what will be displayed?
for (c=1;c<10;c++) {
if (c==5) break;
print c; }

13. The continue statement
used to continue the next iteration in a loop
consider this example. what will be displayed?
for (c=1;c<10;c++) {
if (c==5) continue;
print c; }

14. Labeled code blocks and break and continue
What will this display
mycode: {
print “in my code”;
for (int x=1;x<10;x++) {
if (x==5) break mycode;
print x; }
print “done with loop”

15. Homework Page 214-215 Do number 1, 7 Due in Monday Oct 2
Also write a program to draw a Diamond with a odd input size for example 5
..X..
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