1. CSC 131: Introduction to Computer Science
Dr. Curry Guinn

2. Quick Info Dr. Curry Guinn CIS 2025 guinnc@uncw.edu
Office Hours: MTR: 10:00am-11:00m and by appointment
Teaching Assistant: Zachary Krepps
Tuesday, 8:00am-9:30am, 12:45pm-3:45pm
Thursday, 8:00am-9:30am
Office: GTA office – off of CIS 2004 lab

3. For Next Class, Thursday
Homework 10 is due, Wednesday. We will do most of the work in class. It’s extra credit too, replacing your lowest Homework grade.
Final exam next week, Wednesday, December 6, 11:30am.
Final exam is cumulative
First midterm + second midterm +
UML diagram questions
Tracing a try-except block
Coding:
Create a class in Python based on a UML diagram.

4. Today IDEA : https://uncw.campuslabs.com/courseeval/
Catching exceptions
Object-oriented programming

5. Handling Exceptions What happens when you run this code?
answer = "5.5"
number = int(answer)
print(number)

6. Catching Exceptions
answer = "5.5" try: number = int(answer) print(number) except: print(answer, "is not a valid integer.")

7. Catching Exceptions
answer = "5.5" try: number = int(answer) print(number) except ValueError: print(answer, "is not a valid integer.")

8. Raising Exceptions
print("I will compute the square root") number = input("Enter a number: ") try: num = float(number) if num < 0: raise RuntimeError("You can’t use a negative number") print(math.sqrt(num)) except ValueError: print("That is not a number!") except RuntimeError as e: print(e)

9. UML for BankAccount

10. What other methods might be good for a BankAccount
What other methods might be good for a BankAccount? (Roughly where we were: BankAccount.py and MakeAccounts.py)
def deposit(self, amt):
self.balance += amt
def withdraw(self, amt):
self.balance -= amt
account1 = BankAccount(100, "Jane Doe")
account2 = BankAccount(3000, "Mary Smith")
print(account1)
print(account2)
account1.deposit(75.25)
account2.withdraw(317.18)

11. More on Bank Account Methods that return values
Write calculateInterest such that it returns times the balance.
Test it!

12. Making a list of BankAccounts
Create a loop that iterates 100 times.
Inside of the loop, create a bank account object and add it to a list.
Now, iterate through the list, printing out each bank account.

13. Making random accounts
Here is a list of common first names: FirstNames.txt
Here is a list of common last names: LastNames.txt
Let’s randomly select a first name and a last name to create a random person.
Also, we’ll randomly generate a bank account balance
Now, write this to a file called “accounts.txt”.

14. Reading in some objects
Create a new file, ProcessAccounts.
At the top put
from BankAccount import *
Now have your program open the file accounts.txt
Read in all the bank accounts, creating a corresponding BankAccount object and putting it in a list
Read in a line and split() it.
Use those pieces to build a BankAccount object.

15. Homework 10
0.htm

16. Another Example
Defining a Student object

17. Defining a Student Step 1: What would a UML diagram for a student look like?
Let’s assume we need to store the student’s first name, last name and gpa.
What methods might you want to support?

18. Step 2: Defining the class and the constructor
Create a Python file called “Student”.
Add a constructor that has three instance variables:
firstName
lastName
gpa
In another Python file within the same project (call it Roster), let’s create a few students and print them out.
You’ll need to “from Student import *” to use the Student class in Roster.
Now, test it out by creating a few students and printing out those objects.

19. Step 3: Overriding the __str__ method
Let’s make life easier by re-defining the str method so that it prints out a Student object in a pretty way.

20. Step 4: Reading in students from a file
I’ve created a file roster.txt that contains a list of students in the following format
<last name><SPACE><first name><SPACE><gpa>
In the Roster file, let’s open up the roster.txt file and read in each line.
Now, how do we break up each line so that we can get the individual information?
split()
By splitting the input, we can get each string. Now, you can create a Student object for each line in the input file.
Once you’ve created a Student object, add it to a list of students.
When you’ve finished reading in the whole file, write another loop to print out each student.
How hard would it be to find the student with the greatest GPA?
Try it.