CSE 1310 - Assignments - Programming Assignment 5

The assignments will be graded out of 100 points. Create a text document entitled answers.xxx (where you replace xxx with whatever extension is appropriate, depending on the file format you use). Acceptable file formats are plain text, Word document, OpenOffice document, and PDF. Put your name and UTA ID at the top. Your answers that are not part of a program will be added to this file. Each task below will instruct you where to put your answers.

Task 1 (10 pts.)

What does this function do? What might it be used for? Note: s1 and s2 are strings. Put your answer in answers.xxx.

def function1(s1, s2):
    s1_list = list(s1.lower())
    s2_list = list(s2.lower())
    s1_list.sort()
    s2_list.sort()
    if s1_list == s2_list:
        return True
    else:
        return False

Task 2 (15 pts.)

Describe the execution of this program: what lines are executed; what namespaces come into existence and when; what variables are in each namespace and what are their values? Your answer must explicitly show the state of each namespace after every execution of a line. Put your answer in answers.xxx.

def function1(z):       # line 1
    values = [1, 2, 3]  # line 2
    return values[z]    # line 3
                        # line 4
def function2(x, y):    # line 5
    if y < 0:           # line 6
        val = 0         # line 7
    elif y == 10:       # line 8
        val = 1         # line 9
    else:               # line 10
        val = 2         # line 11
    z = function1(val)  # line 12
    return x*z          # line 13
                        # line 14
x = 10                  # line 15
y = 2                   # line 16
print function2(y, x)   # line 17

Tasks 3, 4, 5 General Instructions

For tasks 3, 4, and 5, you will be writing some useful string processing functions. For each function, you need to:

• In your answers.xxx file, explain the process of how your function will operate and produce the desired result.
• In your answers.xxx file, specify the name of the function, type of input, and type of output.
• Perform error handling (i.e. verifying input is of the proper type, enforcing string length limits, etc) and return a special value if an error is encountered.
• Put the function in a separate file than your main program. Names are provided in the instructions for each task.
• The main program should test your function with interesting cases that show the function works properly. For example, try to "break" your program; try to think of cases that may cause errors (wrong data types, values not obeying constraints, etc) in addition to those that you wouldn't expect to crash the program.
• You are not allowed to use any built-int string methods (i.e. string.method_name())

Task 3 (25 pts.)

It is often useful to split a string at a specified character. As a programmer, you should not have to rely on the language to provide a function to do so. Write a function named split(string, delimiter) that:

• Receives a string string and a string delimiter (a single character) as arguments
• Splits string at each occurrence of delimiter and puts the substrings in a list
• Returns the list of substrings

For example, if I call split("hello:nice to see you:goodbye", ':'), it will return ['hello', 'nice to see you', 'goodbye']. As you can see, it split the string at ':' and put each substring into a list. For this task, delimiter should be a single character. You are not allowed to any of Python's built-in string methods (i.e. string.split()). Save your function in task3_functions.py and your test program as task3_main.py.

Task 4 (25 pts.)

Another useful tool for string processing is the ability to remove certain characters from strings. Write a function called strip(string, characters) that:

• Receives a string string and a string characters as arguments
• Removes the characters found in characters from the beginning and end of string
• Returns the resulting string

For both the left and right side of the string, your function will stop looking for characters to remove when it hits the first character not in characters. So, if I call strip(".$_hello_bye_&", ",&$_."), it will return 'hello_bye', because it removes any of the characters in ",&$_." from the beginning and end. Notice that the function stops stripping on the left when it encounters 'h' and stops stripping on the right when it encounters 'e', since they are not in the list of characters to remove, and leaves the '_' between the words. You are not allowed to use any of Python's built-in string methods (i.e. string.strip(), string.lstrip(), string.rstrip(), etc) in your code. Save your funtion as task4_functions.py and your test program as task4_main.py.

Task 5 (25 pts.)

The final function you will write for string processing joins elements from a list into a string. Write a function join(string_list, join_character) that:

• Receives a list string_list of strings and a string join_character (which is a single character) as arguments
• Joins the strings in the list placing join_character between each string
• Returns the joined string

For example, if I call join(['spam', 'eggs', 'bacon'], '*'), it will return 'spam*eggs*bacon'. You are not allowed to use any of Python's built-in string methods (i.e. string.join()). Save your function in task5_functions.py and your test program in task5_main.py.

Suggestions

Pay close attention to all specifications on this page, including file names and submission format. Even in cases where the program works correctly, points will be taken off for non-compliance with the instructions given on this page (such as wrong file names, wrong compression format for the submitted code, and so on). The reason is that non-compliance with the instructions makes the grading process significantly (and unnecessarily) more time consuming. Contact the instructor or TA if you have any questions.

How to submit

The assignment should be submitted via Blackboard. Submit a ZIPPED directory called assignment5.zip (no other forms of compression accepted, contact the instructor or TA if you do not know how to produce .zip files). The zipped directory should contain your answers.xxx document and all the Python code files (task5.py, task6.py, etc).

Submission checklist

• Is the code running on Python 2.x?
• Did you create the answers.xxx file with your name, UTA ID, and answers to non-programming tasks?
• Did you zip everything into a file called assignment5.zip?