Address Book System in C (File Handling Example)

This project demonstrates an Address Book in C that allows you to add, display, search, update, and delete contacts. It uses structures and file handling to store and manage contact information efficiently.

1. Features

  1. Add new contacts
  2. Display all contacts
  3. Search a contact by name
  4. Update contact details
  5. Delete a contact
  6. Store contacts permanently using files

2. Structure Definition


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct Contact {
char name[50];
char phone[15];
char email[50];
};

3. File-Based Operations


#define FILENAME "contacts.dat"

// Add contact
void addContact() {
struct Contact c;
FILE *fp = fopen(FILENAME, "ab");
if(!fp) { printf("Error opening file.\n"); return; }

printf("Enter Name: "); scanf(" %[^\n]", c.name);
printf("Enter Phone: "); scanf(" %[^\n]", c.phone);
printf("Enter Email: "); scanf(" %[^\n]", c.email);

fwrite(&c, sizeof(c), 1, fp);
fclose(fp);
printf("Contact added successfully!\n");
}

// Display all contacts
void displayContacts() {
struct Contact c;
FILE *fp = fopen(FILENAME, "rb");
if(!fp) { printf("No records found.\n"); return; }

printf("\nName\tPhone\tEmail\n");
while(fread(&c, sizeof(c), 1, fp)) {
printf("%s\t%s\t%s\n", c.name, c.phone, c.email);
}
fclose(fp);
}

// Search contact by name
void searchContact() {
char searchName[50];
struct Contact c;
printf("Enter Name to search: "); scanf(" %[^\n]", searchName);

FILE *fp = fopen(FILENAME, "rb");
if(!fp) { printf("No records found.\n"); return; }

int found = 0;
while(fread(&c, sizeof(c), 1, fp)) {
if(strcmp(c.name, searchName) == 0) {
printf("Name: %s\nPhone: %s\nEmail: %s\n", c.name, c.phone, c.email);
found = 1;
break;
}
}
if(!found) printf("Contact not found.\n");
fclose(fp);
}

// Update contact
void updateContact() {
char searchName[50];
struct Contact c;
FILE *fp = fopen(FILENAME, "rb+");
if(!fp) { printf("No records found.\n"); return; }

printf("Enter Name to update: "); scanf(" %[^\n]", searchName);
int found = 0;

while(fread(&c, sizeof(c), 1, fp)) {
if(strcmp(c.name, searchName) == 0) {
printf("Enter new Phone: "); scanf(" %[^\n]", c.phone);
printf("Enter new Email: "); scanf(" %[^\n]", c.email);
fseek(fp, -sizeof(c), SEEK_CUR);
fwrite(&c, sizeof(c), 1, fp);
printf("Contact updated successfully!\n");
found = 1;
break;
}
}
if(!found) printf("Contact not found.\n");
fclose(fp);
}

// Delete contact
void deleteContact() {
char searchName[50];
struct Contact c;
FILE *fp = fopen(FILENAME, "rb");
FILE *temp = fopen("temp.dat", "wb");
if(!fp || !temp) { printf("File error.\n"); return; }

printf("Enter Name to delete: "); scanf(" %[^\n]", searchName);
int found = 0;

while(fread(&c, sizeof(c), 1, fp)) {
if(strcmp(c.name, searchName) == 0) {
found = 1;
continue; // skip copying
}
fwrite(&c, sizeof(c), 1, temp);
}

fclose(fp);
fclose(temp);
remove(FILENAME);
rename("temp.dat", FILENAME);

if(found) printf("Contact deleted successfully!\n");
else printf("Contact not found.\n");
}

4. Main Menu


int main() {
int choice;
while(1) {
printf("\n--- Address Book ---\n");
printf("1. Add Contact\n2. Display Contacts\n3. Search Contact\n4. Update Contact\n5. Delete Contact\n6. Exit\n");
printf("Enter your choice: "); scanf("%d", &choice);

switch(choice) {
case 1: addContact(); break;
case 2: displayContacts(); break;
case 3: searchContact(); break;
case 4: updateContact(); break;
case 5: deleteContact(); break;
case 6: exit(0);
default: printf("Invalid choice!\n");
}
}
return 0;
}

5. Key Points to Remember

  1. Uses struct to store contact information
  2. File handling ensures permanent storage (fwrite, fread)
  3. Menu-driven program allows easy navigation
  4. Can be extended to include sorting contacts, searching by phone/email, or backup options