COMP10002--Project 1 Solved

1       Learning Outcomes
In this assignment, you will demonstrate your understanding of arrays, pointers, input processing, and functions. You will also extend your skills in terms of code reading, program design, testing, and debugging.

2        The Story...

An emoticon, short for “emotion icon”, is a pictorial representation of a facial expression using characters (punctuation marks only, for this assignment) to express a person’s feelings or mood. As social networks such as Facebook and Twitter and messaging applications such as Snapchat have become part of our daily lives, a large number of emoticons are being used as part of messages and posts. Various individuals and organisations are harvesting and analysing these posts and using emoticons to understand the emotion of the users for business, research, and political decision support.

While emoticons contain rich information, they cannot be handled directly by traditional text analytical tools that were developed based on well written documents such as Wall Street Journal articles. The first step towards utilising emoticon contents is to clean up data and obtain only the valid emoticons. In this assignment, you will learn basic principles in data cleansing and write a program that will cleanse a list of emoticons and find the longest emotion in a post.

3       Your Task
You will be given an input that consists of multiple lines. Each line contains a message from a messaging service with at least 1 and at most 280 characters. There are at least 1 and at most 100 lines. A sample input with five messages is shown below.

That,was,really,funny,=)),:))

I,have,no,clue,:/,:?,on,this,matter

^-^,You,are,the,best,*-*,:-*

See,you,|->,bye

Thank,you,:)

Note that we have replaced all whitespaces (‘ ’) with commas (‘,’) to simplify the debugging and testing process. There will not be any whitespaces in the input data. A comma will not be a part of any emoticon. An emoticon consists of only punctuation marks (no English letters or digits).

At the end of the messages, there is one special line, consists of three hash symbols (“###”). This special line separates the messages from the rest of the inputs. After this special line, there are inputs of multiple lines. These lines are a “dictionary” of emoticons, where each line contains a single emoticon followed by the emotion associated with that emoticon. Each such line has at least 1 and at most 50 characters. There are at least 1 and at most 50 lines. A full sample input including five messages, the separating line, and dictionary of ten emoticons is shown below.

That,was,really,funny,=)),:))

I,have,no,clue,:/,:?,on,this,matter

^-^,You,are,the,best,*-*,:-*

See,you,|->,bye

Thank,you,:)

###

:),happy

:)),happy

^-^,happy

:?,confused

:/,confused

=)),fun

:(,sad

:((,sad

**_**,love

:-*,love

Note that we have replaced all whitespaces (‘ ’) with commas (‘,’) in the dictionary as well. There will not be any whitespaces in the input data.

You will be given a skeleton code file named program.c for this assignment on Canvas. The skeleton code file contains a main function that has been completed already. There are a few other functions which are incomplete. You need to add code into them for the following tasks. Note that you should not change the main function, but you are free to modify any other parts of the skeleton code (including adding more functions).

3.1          Stage 1: Reading the First Message (Up to 3 Marks)
Your first task is to understand the skeleton code. Note the use of the types msg_t and emtcn_t in the skeleton code, which are essentially char type arrays. Each msg_t variable stores the content of a message, and each emtcn_t variable stores the content of an emoticon.

The stage_one function calls the read_one_msg function. You need to add code to the stage_one function to call the read_one_msg function to read the first message. Here, the read_one_msg function is already given to you. The stage_one function then calls the count_tokens function to count and return the number of tokens in the first message. A token is a basic grammatical unit in a sentence. Words and emoticons are both tokens. For simplicity, function count_tokens counts the number of tokens by counting the number of commas, and it should return the number of commas plus 1. You need to add code to complete the function as described above.

The output for this stage given the above sample input should be (where “mac:” is the command prompt; there are 5 commas in the first message, so count_tokens returns 5 + 1 = 6):

mac: ./program < test0.txt

Stage 1

==========

Number of tokens: 6

As this example illustrates, the best way to get data into your program is to edit it in a text file (with a “.txt” extension, jEdit can do this), and then execute your program from the command line, feeding the data in via input redirection (using <). In the program, we will still use the standard input functions such as getchar to read the data fed in from the text file. Our auto-testing system will feed input data into your submissions in this way as well. To simplify the assessment, your program should not print anything except for the data requested to be output (as shown in the output example).

You should plan carefully, rather than just leaping in and starting to edit the skeleton code. Then, before moving through the rest of the stages, you should test your program thoroughly to ensure its correctness.

3.2           Stage 2: Removing Alphanumeric Characters (Up to 7 Marks)
Now add code to the stage_two function to loop through the input messages until reaching the separating line. For each message, your program should cleanse the message by removing all English letters and digits, while keeping all the other characters including commas. On the same sample input data, the additional output for this stage should be:

Stage 2

==========

,,,,=)),:))

,,,,:/,:?,,,

^-^,,,,,*-*,:-*

,,|->,

,,:)

Hint: You may call the read_one_msg function written in Stage 1 to read a message and write another function to cleanse the message. Alternatively, you may write a function to do both in a single pass over the message. The second approach is faster in practice, but we allow both approaches for the purpose of the assignment. In either approach, you need to check whether the line that has been read is the separating line (“###”) or not.

You may assume that no lines will become empty after this stage.

3.3           Stage 3: Removing Extra Commas (Up to 11 Marks)
Add code to the stage_three function to further cleanse the messages by removing any leading, trailing, and consecutive commas. After this cleanse, for every message, there should not be commas at the start or the end. Also, there should be just one comma between any two adjacent tokens remaining in a message. For example, after this stage, a message “,,,,:/,:?,,,” should become “:/,:?”.

The output for this stage given the sample input above is as follows.

Stage 3

==========

=)),:)) :/,:?

^-^,*-*,:-*

|->

:)

Hint: Study the getword function (Figure 7.13 in the textbook, link to source code available in lecture slides lec06.pdf) to learn how to skip leading and trailing commas.

You may assume that no lines will become empty after this stage.

3.4 Stage 4: Reading the Dictionary and Finding the Longest Emoticon (Up to 13 Marks)
Add code to the stage_four function to read the dictionary, that is, the lines after the separating line (“###”) in the input. Recall that, each line in the dictionary contains a single emoticon followed by a text that represents the corresponding emotion. This stage should output the total number of emoticons in the dictionary, the longest emoticon in the dictionary (that is, the emoticon with the maximum length), and its length. Here, the length refers to the number of characters in an emoticon. In the case of ties, the emoticon that appears the earliest in the dictionary should be the output. The output for this stage given the sample input above is as follows.

Stage 4

==========

Emoticon total: 10

Longest: **_**

Length: 5

3.5 Stage 5: Removing Invalid Emoticons with the Help of the Dictionary (Up to 15 Marks)
Note that you are NOT allowed to used any function from the string.h library for Stage 5. You are free to use any library functions in Stages 1 to 4.

Add code to the stage_five function to further cleanse the messages by removing the emoticons that are invalid. For this stage, you need to use the input dictionary of emoticons. That is, if there is no entry for an emoticon in the dictionary, that emoticon needs to be removed from the message. The output for this stage given the above sample dictionary input should be (note a final newline character ‘\n’ at the end):

Stage 5

==========

=)),:)) :/,:?

^-^,,:-*

:)

Here, the emoticon “*-*” in the third message and the emoticon “|->” in the fourth message have been removed as they are not in the dictionary. If a message becomes an empty string after this stage (for example, the fourth message in the sample data), you should not print it. Note that, this stage may again leave extra commas. You do not need to worry about them for the assignment purpose. We design the assignment stages in this order such that you do not need to consider the dictionary in the first three stages.