1. Introduction to Computer Programming
CS 126
Lecture 8
Zeke Maier

2. Plan for Today Questions Administrivia AD Exercises 4.2 & 4.3
Developing
Debugging
Compound Data
Assignment

3. Questions

4. Administrivia http://students.cec.wustl.edu/~ejm3/
Help Session 2-4 in Sever 201
No office hours
Quiz 1 Solutions
Lab 1 Demo Results
Remote Desktop
TA Schedule?

5. AD Exercises 4.2 & 4.3
If you are given three sticks, you may or may not be able to arrange
Exercise 4.2
them in a triangle. For example, if one of the sticks is 12 inches long and the other
two are one inch long, it is clear that you will not be able to get the short sticks to
meet in the middle. For any three lengths, there is a simple test to see if it is possible
to form a triangle:
“If any of the three lengths is greater than the sum of the other two,
then you cannot form a triangle. Otherwise, you can.”
Write a method named isTriangle that it takes three integers as arguments, and that
returns either true or false, depending on whether you can or cannot form a triangle
from sticks with the given lengths.
The point of this exercise is to use conditional statements to write a method that
returns a value.
a. Write the number 1 next to the first statement of this program that will be
executed. Be careful to distinguish things that are statements from things that
are not.
b. Write the number 2 next to the second statement, and so on until the end of
the program. If a statement is executed more than once, it might end up with
more than one number next to it.
c. What is the value of the parameter blimp when baffle gets invoked?
d. What is the output of this program?

6. Developing Development Plan Development Plan Write a method Write more
Compile
Fix syntax errors
Fix semantic errors
Development Plan
Start with a work program
Write a small logical block
Compile & test
Fix errors
the only solution is to remove code until you
have a working program again, and then gradually build the program back up.
-After every change we can see something visible
* If error than we know the error is in the small logical block
AD gives a drawn out example of writing an isIn function. I don’t expect quite as much checking as he does, but some is good!

7. Debugging Determine which type the error is Compiler Errors
Tricks:
* Project->Build Automatically – forces eclipse to recompile the Java code every time you save. When I code its second nature to hit CTRL->S at the end of a logical block/thought to save and get a compilation
* CTRL + SHIFT + F to format a file
* Breakpoints!
Always debug the first error first!
Error messages can be hard to understand, but normally there is useful information lurking inside

8. Compound Data

9. Assignments
Lab 2 due Wednesday
Readings
Monday
KG Notes