Lab 9: Contact List

Due by the end of class

Introduction

You should now be familiar with dynamic memory allocation. In this lab you will be using dynamic memory allocation along with structs and pointers. Feel free to consult the slides for information about using malloc(), free(), and working with structs. You will use these tools to implement a contact list program called contacts.

Lab Exercise

For the lab you will create a library of functions to help manage a list of contacts. Each contact has a name, e-mail address, and an age and will be represented using the following struct. 

typedef struct
{
	char*	name;	// Full name of contact
	char*	email;	// E-mail address of contact
	int	age;	// Age of contact
} Contact;

The list itself will be implemented as a dynamic array (in which the contents are copied over to a larger array if the current one runs out of space). This dynamic array will be stored as the following struct. 

typedef struct
{
	Contact*	contacts;	// Dynamically allocated array of contacts
	int		size;		// Total contacts stored in the list
	int		capacity;	// Size of the array (never less than size)
} ContactList;

See the header file for a complete description of the functions that you'll have to implement. You must include this header file in your code. Through enormous generosity, your instructor has implemented some of these functions (and main()) below that you may copy and paste into your source code. 


int main()
{
	char input;
	char name[NAME_LENGTH];
	char email[EMAIL_LENGTH];
	int age;
	ContactList list;
	Contact* contactPointer = NULL;
	
	list.capacity = 5;
	list.contacts = (Contact*)malloc(list.capacity*sizeof(Contact));
	list.size = 0;
		
	while(  (input = menu()) != 'Q' )
	{
		switch( input )			
		{
			case 'A':	// Add contact
				printf("\tEnter name: ");
				getLine(name);
				printf("\tEnter e-mail: ");
				getLine(email);
				printf("\tEnter age: ");
				scanf("%d", &age);		
				addContact(name, email, age, &list);
				break;
			case 'F':	// Find contact
				printf("\tEnter name: ");
				getLine(name);
				contactPointer = findContact(name, &list);
				if( contactPointer == NULL )
					printf("\t\"%s\" not found\n", name);
				else
					printContact( contactPointer );
				break;			
			case 'P': 	// Print all contacts
				printAllContacts(&list);
				break;
		}
	}

	return 0;
}

char menu()
{  
	int choice;

	// Print menu  
	printf("A - Add a contact\n");
	printf("F - Find and display a contact\n");
	printf("P - Print contact list\n");
	printf("Q - Quit\n");
	printf("Your choice: ");

	// Get input
	while (isspace(choice = getchar()));
	while (getchar() != '\n');

	return toupper(choice);
}

void printAllContacts(const ContactList* list)
{
	int i = 0;

	if (list->size > 0)
	{
		// Print everything
		for (i = 0; i < list->size; ++i)
		{
		  printContact(&list->contacts[i]);
		  printf("\t----------------\n");
		}
	}
	else
		printf("\tContact list is empty!\n");
}

void getLine(char buffer[])
{
	int i = 0;
	int c;
	while ((c = getchar()) != '\n' && c != EOF)
		buffer[i++] = c;
	buffer[i] = '\0';
}

Although an input function, main(), printAllContacts(), and the menu are written for you, you will need to write the addContact(), findContact(), and printContact() functions.

The program starts with a contact list with an initial capacity of 5 contacts. The main() function repeatedly calls the menu() function and responds to the input. If the input is A, it prompts the user for a name, e-mail address, and age and add a contact with that data. You must write the addContact() function that creates a new contact in the list with the given input. Since the Contact struct contains char pointers for the name and the e-mail address, you will need to allocate memory for those strings. The easiest way is to use strdup() inside the addContact() function.

If the user enters F, they will be prompted for a name. Complete the findContact() function that finds the first contact with the matching name or returns NULL if such a contact can't be found.

If the user enters P, all of the contacts will be printed by printAllContacts(). This function calls the printContact() function which you must write, following the format shown in the sample output below:

	Name <e-mail> is age years old.

Finally, if the user enters Q, the program will quit.

Make sure you #include "lab9.h".

Sample Output

Below is sample output from a run of the program. User input is given in green. 

A - Add a contact
F - Find and display a contact
P - Print contact list
Q - Quit
Your choice: a
	Enter name: David Bowie
	Enter e-mail: dbowie@gmail.com
	Enter age: 69
A - Add a contact
F - Find and display a contact
P - Print contact list
Q - Quit
Your choice: a
	Enter name: Chris Avellone
	Enter e-mail: cavellone@obsidian.net
	Enter age: 44 
A - Add a contact
F - Find and display a contact
P - Print contact list
Q - Quit
Your choice: p
	David Bowie <dbowie@gmail.com> is 69 years old.
	----------------
	Chris Avellone <cavellone@obsidian.net> is 44 years old.
	----------------
A - Add a contact
F - Find and display a contact
P - Print contact list
Q - Quit
Your choice: f
	Enter name: Chris Avellone
	Chris Avellone <cavellone@obsidian.net>  is 44 years old.
A - Add a contact
F - Find and display a contact
P - Print contact list
Q - Quit
Your choice: f
Enter name: Bavid Dowie
	"Bavid Dowie" not found
A - Add a contact
F - Find and display a contact
P - Print contact list
Q - Quit
Your choice: q

Hints

  • The realloc() function makes addContact() much easier to write.
  • The strdup() function helps as well.
  • There is only one ContactList. It is declared in main(). Pointers to it are passed to many of the functions.
  • Capacity and size are not the same thing. Capacity is the number of contacts a list can hold. Size is the number it is currently holding.
  • We really should clean up the memory we allocate with free(), but there's too much going on in this lab already. Think about how you would do so for the future.

Turn In

Zip the contents of your lab directory, including the makefile and the source C file. Upload this zip file to Brightspace. Do not include any object files or executables. Running the make command must compile the required C source code file and generate an executable named contacts.

All work must be done individually. Never look at someone else's code. Please refer to the course policies if you have any questions about academic integrity. If you have trouble with the assignment, I am always available for assistance.