| list.C tips |
The lab exercise 1 is to be submitted electronically by 10am January 21st, and covers the work from the first two lab sessions (Jan. 7-9, 14-16), suitably cleaned up to adhere to standards. The submission mechanism is detailed below, and must be followed to obtain credit for the lab.
The exercise will be marked out of 10, and is worth 5% of your total grade.
Late submissions will be penalized 2.5 marks per day late or part thereof.
Exercise details:
In this lab you will create a mechanism to store a collection of names/phone numbers using a linked list, including the ability to read the collection in from a file supplied as a command line argument.
Ultimately, your program will be able to:
Implementation details
The C++ code will be split across three seperate files:
The labex1.C and list.h files will be provided for you, while you will be expected to write and submit the list.C file.
The code below specifies the main routine, datatypes, and function prototypes to be used by the program. It also provides implementations for a number of the supporting functions used by the main routine and the processCommands function.
Your task is to implement the remaining seven functions,
placing the code in list.C:
The functions in your list.C must not require any user input
(i.e. no cin, scanf, etc).
bool insertEntry(string key, string value, keyValue* &list)
bool lookupEntry(string key, string &value, keyValue* list)
keyValue* lookupEntry(string key, keyValue* list)
bool changeEntry(string key, string &value, keyValue* list)
bool deleteEntry(string key, keyValue* &list)
void displayEntries(keyValue* list)
int insertFromFile(char filename[], keyValue* &list)
You are not to alter anything in labex1.C or list.h,
and must put your implementations of those seven functions
in a file named list.C.
Files available here: labex1.C, list.h
// list.h
#ifndef LIST_H
#define LIST_H
#include <string>
#include <iostream>
using namespace std;
// =========================================================
// ====== Data types and constants used in the program =====
// define the contents of a single key/value pair
struct keyValue {
string key; // search key
string value; // associated data value
keyValue *next; // next pair in the list
keyValue *prev; // previous pair in the list
};
// define a maximum length for text
const int MaxTextLen = 256;
// =========================================================
// ====== Prototypes for student-implemented routines ======
// insertEntry
// -----------
// adds one key/value pair to the front of the list
// as long as the key does not already appear in the list
// returns true if successful, false otherwise
bool insertEntry(string key, string value, keyValue* &list);
// lookupEntry (internal use)
// -----------
// search the list for an entry matching the specified key,
// return a pointer to the entry if found,
// return null otherwise
keyValue* lookupEntry(string key, keyValue* list);
// lookupEntry (public use)
// -----------
// search the list for an entry matching the specified key,
// set the matching value and return true if found,
// return false otherwise
bool lookupEntry(string key, string &value, keyValue* list);
// changeEntry
// -----------
// search the list for an entry matching the specified key,
// set the new matching value and return true if found,
// return false otherwise
bool changeEntry(string key, string &value, keyValue* list);
// deleteEntry
// -----------
// search the list or an entry matching the specified key,
// remove the entry from the list, delete it,
// and return true if found,
// return false otherwise
bool deleteEntry(string key, keyValue* &list);
// displayEntries
// --------------
// display each key/value pair in the list,
// with one key/value pair per line of output
void displayEntries(keyValue* list);
// insertFromFile
// --------------
// if the specified file cannot be opened return -1,
// otherwise
// add each key/value pair in the file to the list
// returning a count of the total number of successful inserts
// assumes the file contains an even number of lines,
// alternating between keys and values, e.g.
// Fred Jones
// 555-123-4567
// Scoobert Doo
// 555-987-6543
// etc.
int insertFromFile(char filename[], keyValue* &list);
#endif
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// labex1.C
#include "list.h"
// define the valid single-character commands
enum Command {
QuitCmd = 'Q', InsertCmd = 'I',
EditCmd = 'E', LookupCmd = 'L',
HelpCmd = 'H', RemoveCmd = 'R',
PrintCmd = 'P', FileInsertCmd = 'F',
InvalidCmd = '-'
};
// =========================================================
// ====== Prototypes for provided support routines =========
// read a name from the user
// and store it in the parameter provided
void getName(string &name);
// read a phone number from the user
// and store it in the parameter provided
void getNumber(string &number);
// display the list of valid commands
void printCommands();
// read and return a valid single-character command,
// limits to one command per line
// (anything beyond the first command is discarded)
Command getCommand();
// process a command and update the name/number list
void processCommand(Command cmd, keyValue* &phoneBook);
// =========================================================
// ====== Provided main routine ============================
int main(int argc, char* argv[])
{
// current list of messages, initially empty
keyValue *phoneBook = NULL;
// current user command
Command cmd;
// display the welcome message
cout << "Welcome to the phonebook system\n" << endl;
// load names/numbers from the file specified in
// the command line argument (if any)
if (argc > 1) {
int numLoaded = insertFromFile(argv[1], phoneBook);
if (numLoaded < 0) {
cout << "Attempt to load from file \"" << argv[1];
cout << "\" was unsuccessful" << endl;
} else {
cout << "Load from file \"" << argv[1];
cout << "\" inserted " << numLoaded << " entries\n" << endl;
}
}
// display the command list on startup
printCommands();
// keep obtaining and processing commands
// until the user decides to quit
do {
cmd = getCommand();
processCommand(cmd, phoneBook);
} while (cmd != QuitCmd);
// shut down
cout << "Exiting the phonebook system\n" << endl;
return 0;
}
// =========================================================
// ====== Implementations of provided support routines =====
// read a name from the user
// and store it in the parameter provided
void getName(string &name)
{
char text[MaxTextLen];
cout << "Please enter the name of the person or organization" << endl;
cin.getline(text, MaxTextLen);
name = text;
}
// read a phone number from the user
// and store it in the parameter provided
void getNumber(string &number)
{
char text[MaxTextLen];
cout << "Please enter the phone number of the person or organization" << endl;
cin.getline(text, MaxTextLen);
number = text;
}
// display the list of valid commands
void printCommands()
{
cout << "Enter " << (char)(HelpCmd) << " to print this menu,\n";
cout << " or " << (char)(InsertCmd) << " to insert a new phone book entry,\n";
cout << " or " << (char)(PrintCmd) << " to print the phone book contents,\n";
cout << " or " << (char)(LookupCmd) << " to lookup a phone number,\n";
cout << " or " << (char)(EditCmd) << " to edit someone\'s phone number,\n";
cout << " or " << (char)(RemoveCmd) << " to remove a phone book entry,\n";
cout << " or " << (char)(QuitCmd) << " to quit,\n" << endl;
}
// read and return a valid single-character command
// limits to one command per line
// (anything beyond the first command is discarded)
Command getCommand()
{
char cmd = QuitCmd;
char junk[MaxTextLen]; // used to discard rest of line
do {
cout << "Please enter a command: ";
cin >> cmd;
cin.getline(junk, MaxTextLen);
cmd = toupper(cmd);
switch (cmd) {
case HelpCmd: return HelpCmd;
case InsertCmd: return InsertCmd;
case PrintCmd: return PrintCmd;
case LookupCmd: return LookupCmd;
case EditCmd: return EditCmd;
case RemoveCmd: return RemoveCmd;
case QuitCmd: return QuitCmd;
default:
cout << "Invalid command entered: " << cmd << endl;
cout << "Please try again" << endl;
cmd = InvalidCmd;
break;
}
} while (cmd == InvalidCmd);
return InvalidCmd;
}
// process a command and update the name/number list
void processCommand(Command cmd, keyValue* &phoneBook)
{
string name, number;
switch (cmd) {
case HelpCmd:
printCommands();
break;
case InsertCmd:
getName(name);
getNumber(number);
cout << "Insert attempt (";
cout << name << ":" << number << ")" << endl;
if (insertEntry(name, number, phoneBook)) {
cout << "...succeeded" << endl;
} else {
cout << "...failed" << endl;
}
break;
case PrintCmd:
cout << "Phone book contents:" << endl;
displayEntries(phoneBook);
break;
case LookupCmd:
getName(name);
cout << "Lookup attempt for " << name << endl;
if (lookupEntry(name, number, phoneBook)) {
cout << "...number is " << number << endl;
} else {
cout << "...no entry found" << endl;
}
break;
case EditCmd:
getName(name);
getNumber(number);
cout << "Edit attempt for " << name << endl;
if (changeEntry(name, number, phoneBook)) {
cout << "...new number is " << number << endl;
} else {
cout << "...no entry found" << endl;
}
break;
case RemoveCmd:
getName(name);
cout << "Attempting to remove entry for " << name << endl;
if (deleteEntry(name, phoneBook)) {
cout << "...succeeded" << endl;
} else {
cout << "...failed - no entry found" << endl;
}
break;
case QuitCmd:
// no action required
break;
default:
cout << "Invalid command supplied, please try again\n";
printCommands();
break;
}
}
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Recommended development sequence
I strongly advise you follow a well-thought out sequence of development steps in completing the exercise. The set below would be a reasonable starting point:
PHASE 0
PHASE I
PHASE II
Note that phase II deals entirely with the implementation of the insertFromFile function.
Submission mechanism
All the code for the list functions must be in a single file named list.C (correct spelling and capitalization is essential for the submission to work correctly).
To submit the assignment, cd to the directory that contains your labex1 files and type the following command:
/home/faculty/wesselsd/bin/submit 161 list.C
Marking guidelines:
Marks will be based on meeting all the criteria below:
Code standards:
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