Lab 3: Managing a C project

The goal of this lab is to work on a collaborative project using the project management tools we saw in class yesterday. It also introduces C programming with structs.

In this lab, you will work in pairs but each pair will work on different parts of the project, with one product produced at the end. The work of the two pairs will be coordinated using Mercurial.

1. Introduction

You are writing software for a Twitter knock-off called Chatter. In the Chatter system, users send messages at most 140 characters long. Additionally, each message has the user id of the user who sent the message (at most 16 characters long), a time stamp indicating the time the message was sent (a long int indicating the number of milliseconds since midnight, Jan 1, 1970), and up to 5 hash codes indicating categories or topics the message falls under (each hash code is at most 10 characters long).

I have provided some code for producing "random" text components and "random" user names. Your tasks will include designing and implementing a struct to represent messages, writing functions for displaying and sorting messages, and completing drivers to test these messages.

2. Set up

Even though we are continuing your work from last week, set up a new directory for this lab and move into it.

mkdir lab3
cd lab3

Now, get your local repository and working copy

hg clone /homes/tvandrun/Public/cs245/repositories/chatter

3. Given code

The chatterUtil library provides the following functions:

• randomInt(): produce a random int between 0 (inclusive) and a given int (exclusive). So randomInt(4) will return 0, 1, 2, or 3, with equal probability.
• getTimeMillis(): return the current time
• fillRandomText(): fill the given char array with a string containing a randomly chosen text for a chatter message
• fillRandomUserName(): fill the given char array with a string containing a randomly chosen text for a user name

3. Tasks

You need to complete the following tasks:

• Design and implement the struct to represent messages. I have already set up a dummy struct for a struct message type. You need to complete that struct according to the description of a message given above. Since the struct type needs to be seen by the library and the drivers, it is defined in message.h
• Make a new random message. The headerfile message.h gives the prototype for the function newRandomMessage() which is used by the two driver programs. Write a definition for this function in an implementation file for the message library. Use the functions from chatterUtil to produce the text, user name, and hash codes.
• Display a message. The headerfile message.h gives the prototype for the function display() which displays a message to the screen, nicely formatted, showing all the information stored about that message. The driver displayDriver tests this.
• Sort messages by username. The headerfile message.h gives the prototype for the function sortByUserName, and the driver sortDriver.c uses it. This function must be completed so that it sorts an array of messages by user name, alphabetically.
• Finish the sortDriver. The sortDriver program is intended to display all the usernames in the array of messages after sorting, to search the array for a message containing a given hashcode, and then to sort the mssages by date. Finish the driver so that it exercises these things, adding appropriate functions to the library as necessary. For example, you will need to write a sortByDate() function or the equivalent.
• Design a makefile. A makefile needs to be written and, possibly, maintained as you work on this lab.

Divide this work between the two groups and sync up as you go along so you can test the code as you go.