CIS 122  Project 8

1
CIS 122  Project 8 debug files,
find and fix errors

Introduction to debugging
Everyone who programs must learn to debug programs.
There are 3 major categories of bugs:
1. Violation of Python language rules
Example
if x = 3:
This should have a double equals == to compare x to 3.
Python gives you error messages about rule violations.
print("Hello Jane"
number = 6 Python complains of a syntax error here,
but it really is caused by an error on the previous statement.
2. Errors that occur when running your program
option = "b"
print(options)# When run, gets undefined variable options
3. Program runs without obvious errors but does not solve the
problem it was designed to solve.
The Mars Observer radar unit correctly measured the height
of the satellite above Mars and sent the number of feet
above Mars to the altitude adjustment module which expected
to get the number of meters.
In this project, you will run programs, note the errors and correct
them.
We'll start with a very simple program with just one error
error0.py
Identify the fixes you make with a
#-- (brief description of your fix or fixes)
The fixed version:
Generally, if you find one error, there is a very good chance that
there is another error (or more!) still present in your program.
Another example, that may have more than one error
You type 1000 for the number of pesos and the program
announces that they are worth 0.02 euros.
You notice that the function gets called and appears to calculate
correctly.
This looks like a possible fix.
#--Assigned result of function call to euros
euros = pesos_to_euros(pesos)
The program now calculates 50 pesos will be worth 1 euro.
What about 100.5 pesos? That gets an error. Maybe we should
allow float values instead of int.
Type number of pesos: 50.77
50.77 pesos are worth 1.0154 euros
Rounding the number of euros would help.
Here is a fixed version of the program; it repairs the errors of the
program.
Bonus work on this example would be to introduce a while loop to
allow changing a number of different peso amount to euros…
Except for an exercise, do not work with these examples, instead,
work on the following programs.
2
P8_1_unending.py
5 points
Symptom: When I run this program, I have to keep adding names; I don't have an option to Quit.
Fix the program, save it as P8_1_fixed.py
Rubric
2 points #-- tells what changes you made to fix the program
3 points Actual fixes correct the program.
# P8_1_unending.py
# Help - when I run this program it keeps going and going...
my_list = ['Jim', 'Ashley', 'Amanda', 'Zelda']
# Add more names
hint = "Type Q to quit or first name to add (such as Anne): "
name = input(hint).title()
while name != 'Q':
my_list.append(name)
print("Added", name)
Example of program output when fixed (includes print of list)
3
P8_2_oops.py
5 points
Symptom: When I run this program, I cannot find names like Amanda that are in the list.
Fix the program, save it as P8_2_fixed.py
Rubric
2 points #-- tells what changes you made to fix the program
3 points Actual fixes correct the program.
# P8_2_oops.py
# Help - when I run this program it does not work right.
# I cannot find names like amanda that are in the list
#
def search(who, names):
''' Return index of name or None if not found'''
index = 0
for person in names:
if person == who:
return index
else:
return None
my_list = ['jim', 'ashley', 'amanda', 'zelda', 'brittany']
my_gpa = [3.05, 4.01, 2.87, 4.20, 1.95]
hint = "Type Q or type a name to search for (such as Jim): "
find_me = input(hint).lower()
while find_me != 'Q':
index = search(find_me, my_list)
if index == None:
print(find_me, 'NOT found in names list')
else:
print(find_me, 'found at offset', index, 'in names list')
print(find_me, 'has a', my_gpa[index], 'grade point average')
find_me = input(hint).lower()
Example of minimal fix (5 points)
Example of better fix (5 points + 1 bonus)

4
P8_3_fixme.py
10 points
Symptom: When I run this program, I cannot find names like Amanda that are in the list.
Fix the program, save it as P8_3_fixed.py
Rubric
4 points
#-- identifies each of several flaws in the program and tells what you did to fix each one.
6 points A series of actual fixes correct the program.
# P8_3_fixme.py
# Help - when I run this program it does work right.
# It does not find names like ashley in the names list
#
def linear_search(who, names):
''' Return index of name or None if not found'''
index = 0
for person in names:
if person == who:
return index
elif person who:
return None
return None
names = ['jim', 'tom', 'ashley', 'amanda', 'brittany', 'megan']
hint = "Type Q or type a name to search for (such as jim): "
find_name = input(hint).lower()
while find_name != 'Q':
index = linear_search(find_name, names)
print()
if index == None:
print(find_name, 'NOT found in names list')
else:
print(find_name, 'found at offset', index, 'in names list')
print()

find_name = input(hint).lower()
There may be several strategies for fixing this program.
Clearly identify what strategy you are using to fix the program.
Then test your fixed program to make sure it works correctly.
Example of fix (capital names are optional) Another solution gives this:

P8_4.py
5
5 points
Symptom: When I run this program, I get a syntax error.
Fix the program, save it as P8_4_fixed.py
Rubric
2 points #-- tells what changes you made to fix the program
3 points Actual fixes correct the program.
# P8_4.py
# Display options, do the right thing, repeat
def get_option(my_codes, my_descriptions):
''' Display codes and descriptions from lists
Ask user to choose a code
Return user choice as single lower-case character
'''
for count in range(len(my_codes)):
print(my_codes[count], my_descriptions[count])
answer = input("Type your choice: ")
option = answer[0].lower()
for code in my_codes:
if code[0].lower() == option:
return option
print("\nPlease try again")
return get_option(my_codes, my_description)
codes = ['Q', 'B', 'S', 'P']
descr = ['Quit', 'Buy', 'Sell', 'Panic']
while True == True:
choices = get_option(my_codes, my_descriptions)
if choice == 'Q':
break
elif choice = 'B':
print("Buy more and save even more!")
elif choice = 'S':
print('Sell and earn big money now!')
elif choice = 'P':
print('The yen is down, oil is down, abandon all hope - PANIC')
print("Done")
Example of fix