Statement of the Problem: This assignment involves modeling a very simple email

Question

Statement of the Problem:

This assignment involves modeling a very simple email system. All the email messages are addressed to you. Each email message has several data field: (1) a from-field (who it is from), (2) a date field, (3) a subject field, and (4) a body field (the text of the message). Given as input a group of email messages (each having all the fields just indicated), listed from the oldest message to the most recent, your program should be able to respond to queries of the following kinds:

§ Sort (arrange) and display the received messages from the most recent to the least recent

§ Delete the most recent message

§ Display all the (non-deleted) messages from a given sender, arranged the most recent to the least recent

§ Display a given message

The precise formatting of the input, the queries, and the answers of your program is detailed below.

The Input:

Your program will take two input files from the command prompt, the first file containing information about the email messages, and the second file containing the queries that your program should answer.

The first input file, called the messagesfile.txt, which contains the messages, will be such that each message has one "paragraph" of several lines, and each message is separated from the next with a line consisting of ##########, that is, 10 consecutive occurrences of #. The format of the paragraph of a message is:

FROM: a string of at most 50 characters representing the email address of the sender. It has no blanks.

DATE: a data, formatted as MM-DD-YYYY

SUBJECT: a line of at most 60 characters
BODY: a string (one or more lines starting at the next line below). It can have of any number of characters, such that no line begins with ##########


Note that for the date, MM is a 2-digit number representing the number of the month; for example, MM=01 for January, MM=03 for March, and MM=11 for November. DD is a 2-digit number representing the day of the month (between 01 and 31). YYYY is a 4-digit number representing the year.

Note that you are guaranteed that each message in messagesfile.txt is more recent (has later date) than all the messages before it in that file.



The second input file, called the queriefile.txt, will have a sequence of queries, one query per line, where each query is any of the following:

LIST-MESSAGES-BY-DATE

LIST-MESSAGES-FROM email-address-string

DELETE-MOST-RECENT-MESSAGE

DISPLAY k

Note that each of those queries could repeat multiple times in the queries file.

Here is an explanation of each kind of query.

§ The first kind of query asks you to list all the undeleted messages, arranged from the most recent to the least recent message.

§ The 2nd kind of query asks you to list all the undeleted messages from the sender whose email address is the specified email-address-string. The messages must be arranged from the most recent to the least recent message.

§ The 3rd kind of query asks you to delete the most recent message.

§ The 4th kind of query asks you to show (output) the body of the kth most recent message in the remaining list of undeleted messages.

The output:

Your program must take as input the two input files above, in that order. That is, we should be able to compile your program into an executable file (called Program1, say), then call it from the command-line like this:

./Program1 messagesfile.txt queriesfile.txt

Your program must then write the output to the standard output (using printf). The output of the first two kinds of query should begin by repeating the same query on a new line, followed by a colon (:), followed on the next line by a sequence of lines, one line per message; each line will have the email address of the sender, then the subject of the message, and finally the date of the message (using the same date format as explained above). Put ## between each field and the next in each line. (see the sample input and output for illustration)

The output of the 3rd kind of query has two line, where the first is “DELETE-MOST-RECENT-MESSAGE:” and the second line is “DELETED MESSAGE” or “THERE ARE NO MESSAGES TO DELETE”.

The output of the 4th kind of query should begin on a new line with

MESSAGE k:

followed on the next line with the body of the kth message, in exactly the same as it was given in the messages input file, but without the ##########.

If there is no output for one of the first, second, and fourth kinds of query, you output the word NONE.

Finally, the output of each query must be followed by ########## on a new line, and then by a blank line.

Explanation / Answer

What program are you using?

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