Phone book

The program phone_book.c is a partially completed phone book program. It is a command line program that will maintain a database of phone numbers and names in a file directory.db.

It can be used in the following way.

./phone_book add name number This command is used to add the name and number to the database. If the database file (
./phone_book list This command will list all the users and numbers in the system
./phone_book search name This command will search for the entry with name name and print the phone number if name exists. Otherwise it will print no match and exit with a non-zero status.
./phone_book delete name This command will search for the entry with name name and delete it from the database if name exists. Otherwise it will print no match and exit with a non-zero status.

Design notes

The program loads the entries in the database into a linked list. Each node of the list contains the name and phone number.

The program has decent error checking. It will abort if you try to list when the database file is non existent. It will also print proper error messages if you type a wrong or malformed command.

The program allocates memory to create the linked list. It should be fully freed before the program exits. valgrind should show no leaks possible.

Example usage

A pre compiled version of the program with all the features mentioned below is available in the repository as good_phone_book. You can use this to compare the output of your program.

Error handling

%  ls directory.db
/bin/ls: cannot access 'directory.db': No such file or directory                                              
% ./phone_book list
Couldn't open database file: No such file or directory
% ./phone_book search john
Couldn't open database file: No such file or directory
% ./phone_book delete john
Couldn't open database file: No such file or directory

Adding and listing

% ./phone_book add john 1234567890
% ./phone_book list
john                 : 1234567890
Total entries :  1
% ./phone_book add james 0987654321
% ./phone_book list
john                 : 1234567890
james                : 0987654321
Total entries :  2

Searching

% ./phone_book search mary
no match
% ./phone_book search james
0987654321

Deleting

% ./phone_book add jack 5432167890
% ./phone_book delete mary
no match
% ./phone_book list
john                 : 1234567890
james                : 0987654321
jack                 : 5432167890
Total entries :  3
% ./phone_book delete james
% ./phone_book list
john                 : 1234567890
jack                 : 5432167890
Total entries :  2
% ./phone_book delete john
% ./phone_book list
jack                 : 5432167890
Total entries :  1

Tasks

There is a comment "TBD" in various parts of the phone_book.c file to indicate what parts of the code need to be implemented.

The total entries is not currently printed by the list command. This needs to be fixed.
The delete functionality has to be implemented similar to the others (including error checking etc.). The command line parsing works but it doesn't actually do any deletion. Make sure that all files are closed and all memory is freed.
The search functionality is not implemented. The command is also not recognised. This needs to be fixed. Make sure that all files are closed and all memory is freed.
The free_entries function should walk through the linked list and free all the nodes in it. It's not implemented. You can check to see if it's properly implemented and running
```
  valgrind ./phone_book search jack
```
The output of valgrind should have a line like this. This will happen only if free_entries is properly implemented and all memory is freed.
```
    All heap blocks were freed -- no leaks are possible
```

Genskill2/008-phone-book-Nacn3