1. Agenda Remarks about last homework for loop Nested for loop Flowchart
Debugging techniques
breakpoint; variable trace; println
Homework

2. Remarks on the last homework
Do NOT declare variable inside the loop
Good design needs some thinking and trying
- if you want the user to play until he/she gets
it right?...what if it is hard to be right?
- the program quits when user enters some
number? Is it the way we play games?

3. for Loop
for Loop executes a set of statements a fixed number of times. The for statement takes the form:
for (<initialization>; <condition>; <increment>) {
<statements> }
example
for (int i = 1; i <= 10; i++) {
System.out.println(i);
How can this example change to equivalent while or do-while loop?

4. Practice for loop
In each problem below state what is printed unless directed otherwise.
1. int j=0;
for(int g=0; g< 5; g++)
j++;
System.out.println(j);
int s=1;
for(int j=3; j >+0; j--) {
s = s+j; }
System.out.println(s);

5. Nested for loop When one loop is placed inside another loop
for(int j=0; j < 5; j++) {
System.out.println(“outer loop”);
for(int k = 0; k < 8; k++)
{ System.out.println(“inner loop”); } }

6. Flowchart
It allows user to design the logical flow of a program without first getting into the details of specific code.
Flowcharts use symbols and text to give a visual representation of a solution.
indicates start or end.
indicates input/ouput.
indicates a decision
indicates the process

7. The BirthdayGame flowchart
Start
birthDay = number %100
Display steps for calculating numbers
Display player’s birthday
Prompt user for number
End
Substract 165 from numbers
birthMonth = number/100

8. Example of decision symbol
yes no
If (input number==secrete number)?
Display “sorry, better luck next time”
Display “you guess it”

9. Debugging Technique
Debugging is the process of getting an application to work correctly.
Additional println
Adding println() statements just after a variable is
assigned a new value or before and after a condition is evaluated can help detect the source of a logic error.
Variable trace
A variable trace is a table listing the values of
variables at the points of assignment
Debugger breakpoint

10. Println debugging example
int num1 =0;
int num2 = 0;
while (num1 < 10) {
if (num1 % 3 == 0)
num2 = num2 + num1;
System.out.println(num2 + “ “ ); }
num1++

11. Variable trace
num1
Num2
output 1 2 3 4 5 6 7 8 9

12. Practice for homework
* ** *** **** ***** ****** *******
If we wanne print out the picture on the left, using the for loop?

13. Homework
I. Draw a flowchart on the program gradeSystemConversion II. Using a for loop to print out a star triangle upside down like the following: ****** ***** **** *** ** *