Contact Book Application using C
Last Updated :
10 Jun, 2025
A Contact Book is a simple application to store and manage people's contact information such as names and phone numbers. We will create a simple console-based C contact book in this project.
Our contact book application will have following features:
- Add New Contact: Insert name and phone number into the contact book.
- Search Contact: Search a contact using recursion, by name or phone number.
- Display All Contacts: Show all saved contacts.
- Delete Contact: Remove a contact by name or number.
Project Requirements
To do this project, the programmer must be familiar with the following C concepts:
- Decision Making and Loops
- Input/Output and Functions
- Arrays, Strings and Pointers
Additionally, we will need a working C development environment to create and test the application. Refer to this if you want to revise - C Tutorial
Implementation
Let's start working on this project:
STEP 1: Basic Setup
First, we need to create some variables to store the data such that they are accessible to whole program. For this purpose, we use global variables.
- We create two parallel 2d character arrays: names[i] and phones[i], which together represents one contact.
- A count integer that keeps track of how many contacts are currently stored.
C
#include <stdio.h>
#include <string.h>
// Max number of contacts
#define MAX 100
// Parallel arrays to store names and phones
char names[MAX][100];
char phones[MAX][15];
// Number of contacts
int count = 0;
We also created a constant macro MAX to specify the maximum number of contacts it can store.
STEP 2: Creating "Add New Contact" Feature
In this step, we create a function that can add contact to the parallel arrays. While adding contact, we also make sure that the given number is valid.
C
int isValidPhone(const char *phone) {
int len = strlen(phone);
// Remove newline if present (for fgets compatibility)
if (phone[len - 1] == '\n') len--;
// Length must be between 7 and 14
if (len < 7 || len > 14)
return 0;
// Must contain only digits
for (int i = 0; i < len; i++) {
if (phone[i] < '0' || phone[i] > '9')
return 0;
}
return 1;
}
// Add new contact
void addContact() {
if (count >= MAX) {
printf("Contact book is full!\n");
return;
}
printf("Enter name: ");
fgets(names[count], sizeof(names[count]), stdin);
trimNewline(names[count]);
while (1) {
printf("Enter phone number: ");
fgets(phones[count], sizeof(phones[count]), stdin);
trimNewline(phones[count]);
if (isValidPhone(phones[count])) {
break; // valid number
} else {
printf("Invalid phone number! It must be 7-14 digits and contain only numbers.\n");
}
}
printf("Contact added successfully.\n");
count++;
}
The fgets() is used to read the full string (including spaces).
STEP 3: Display All Contacts
We just need to iterate through both the arrays simultaneously and print the contacts one by one.
C
void displayContacts() {
if (count == 0) {
printf("No contacts to display.\n");
return;
}
printf("\n--- Contact List ---\n");
for (int i = 0; i < count; i++) {
printf("%d. Name: %s, Phone: %s\n", i + 1, names[i], phones[i]);
}
}
STEP 4: Search by Name
To find the matching name, we use strcmp() function with the target name and all the names in the names[] array. We have used recursion to implement this, but it can also be implemented using iteration.
C
int searchByName(int index, const char *query) {
if (index == count)
return -1;
if (strcmp(names[index], query) == 0)
return index;
return searchByName(index + 1, query);
}
The extra argument index is used to change the search element in each recursive call.
STEP 5: Recursive Search by Phone
Similar to search by name, the search by phone feature can be implemented.
C
int searchByPhone(int index, const char *query) {
if (index == count)
return -1;
if (strcmp(phones[index], query) == 0)
return index;
return searchByPhone(index + 1, query);
}
STEP 6: Delete Contact by Name
We cannot actually delete an element in arrays, so we have to implement a workaround.
- If the contact is the last element, just decrease the count.
- If the contact is not last element, copy the last contact to its position and then decrease the count.
C
void deleteContact() {
char query[100];
int index;
printf("Enter the name to delete: ");
fgets(query, sizeof(query), stdin);
trimNewline(query);
index = searchByName(0, query);
if (index == -1) {
printf("Contact not found.\n");
return;
}
// If it's the last contact, just reduce count
if (index == count - 1) {
count--;
}
// Else, copy last to current index and reduce count
else {
strcpy(names[index], names[count - 1]);
strcpy(phones[index], phones[count - 1]);
count--;
}
printf("Contact deleted successfully.\n");
}
STEP 7: Dashboard
The final step is to create a dashboard or a menu using which the user can use this application. It should provide options to select all the functionality. You can also add desired cosmetic elements to improve readability and accessibility.
C
int main() {
int choice;
char query[100];
int index;
while (1) {
printf("\n--- Contact Book Menu ---\n");
printf("1. Add Contact\n");
printf("2. Search by Name\n");
printf("3. Search by Phone\n");
printf("4. Display All Contacts\n");
printf("5. Delete Contact\n");
printf("6. Exit\n");
printf("Enter your choice: ");
scanf("%d", &choice);
getchar(); // clear leftover newline from input buffer
switch (choice) {
case 1:
addContact();
break;
case 2:
printf("Enter name to search: ");
fgets(query, sizeof(query), stdin);
trimNewline(query);
index = searchByName(0, query);
if (index == -1)
printf("Contact not found.\n");
else
printf("Found: Name: %s, Phone: %s\n", names[index], phones[index]);
break;
case 3:
printf("Enter phone number to search: ");
fgets(query, sizeof(query), stdin);
trimNewline(query);
index = searchByPhone(0, query);
if (index == -1)
printf("Contact not found.\n");
else
printf("Found: Name: %s, Phone: %s\n", names[index], phones[index]);
break;
case 4:
displayContacts();
break;
case 5:
deleteContact();
break;
case 6:
printf("Exiting Contact Book. Goodbye!\n");
return 0;
default:
printf("Invalid choice. Try again.\n");
}
}
return 0;
}
In the above menu, an infinite loop is used to make the application run until the user wants to exit.
Execution
Combining each of these elements, we get the executable source code:
C
// Complete Source Code (Click to expand)
//Driver Code Starts
#include <stdio.h>
#include <string.h>
// Max number of contacts
#define MAX 100
// Parallel arrays to store names and phones
char names[MAX][100];
char phones[MAX][15];
// Number of contacts
int count = 0;
// Helper to remove newline character from fgets
void trimNewline(char *str) {
int len = strlen(str);
if (len > 0 && str[len - 1] == '
')
str[len - 1] = ' ';
}
int isValidPhone(const char *phone) {
int len = strlen(phone);
// Remove newline if present (for fgets compatibility)
if (phone[len - 1] == '
') len--;
// Length must be between 7 and 14
if (len < 7 || len > 14)
return 0;
// Must contain only digits
for (int i = 0; i < len; i++) {
if (phone[i] < '0' || phone[i] > '9')
return 0;
}
return 1;
}
// Add new contact
void addContact() {
if (count >= MAX) {
printf("Contact book is full!
");
return;
}
printf("Enter name: ");
fgets(names[count], sizeof(names[count]), stdin);
trimNewline(names[count]);
while (1) {
printf("Enter phone number: ");
fgets(phones[count], sizeof(phones[count]), stdin);
trimNewline(phones[count]);
if (isValidPhone(phones[count])) {
break; // valid number
} else {
printf("Invalid phone number! It must be 7-14 digits and contain only numbers.
");
}
}
printf("Contact added successfully.
");
count++;
}
// Display all contacts
void displayContacts() {
if (count == 0) {
printf("No contacts to display.
");
return;
}
printf("
--- Contact List ---
");
for (int i = 0; i < count; i++) {
printf("%d. Name: %s, Phone: %s
", i + 1, names[i], phones[i]);
}
}
// Recursive search by name
int searchByName(int index, const char *query) {
if (index == count)
return -1;
if (strcmp(names[index], query) == 0)
return index;
return searchByName(index + 1, query);
}
// Recursive search by phone
int searchByPhone(int index, const char *query) {
if (index == count)
return -1;
if (strcmp(phones[index], query) == 0)
return index;
return searchByPhone(index + 1, query);
}
// Delete contact using efficient swap-from-last method
void deleteContact() {
char query[100];
int index;
printf("Enter the name to delete: ");
fgets(query, sizeof(query), stdin);
trimNewline(query);
index = searchByName(0, query);
if (index == -1) {
printf("Contact not found.
");
return;
}
// If it's the last contact, just reduce count
if (index == count - 1) {
count--;
}
// Else, copy last to current index and reduce count
else {
strcpy(names[index], names[count - 1]);
strcpy(phones[index], phones[count - 1]);
count--;
}
printf("Contact deleted successfully.
");
}
// Main menu
int main() {
int choice;
char query[100];
int index;
while (1) {
printf("
--- Contact Book Menu ---
");
printf("1. Add Contact
");
printf("2. Search by Name
");
printf("3. Search by Phone
");
printf("4. Display All Contacts
");
printf("5. Delete Contact
");
printf("6. Exit
");
printf("Enter your choice: ");
scanf("%d", &choice);
getchar(); // clear leftover newline from input buffer
switch (choice) {
case 1:
addContact();
break;
case 2:
printf("Enter name to search: ");
fgets(query, sizeof(query), stdin);
trimNewline(query);
index = searchByName(0, query);
if (index == -1)
printf("Contact not found.
");
else
printf("Found: Name: %s, Phone: %s
", names[index], phones[index]);
break;
case 3:
printf("Enter phone number to search: ");
fgets(query, sizeof(query), stdin);
trimNewline(query);
index = searchByPhone(0, query);
if (index == -1)
printf("Contact not found.
");
else
printf("Found: Name: %s, Phone: %s
", names[index], phones[index]);
break;
case 4:
displayContacts();
break;
case 5:
deleteContact();
break;
case 6:
printf("Exiting Contact Book. Goodbye!
");
return 0;
default:
printf("Invalid choice. Try again.
");
}
}
return 0;
}
//Driver Code Ends
On executing this code, we get the following output:
Similar Reads
Bank account system in C using File handling This article focuses on how to create a bank account system using C language and File handling in C. Approach:Let's discuss the approach in detail, covering all the functions and their explanation in detail- Create a Menu in the main function and create different functions for the Menu, which will b
12 min read
Shopping Cart Project Using C Language Online Shopping applications are one of the favorite applications out of all online applications. It is a very much used application in everyone's life. So, Let's try to create a Shopping cart using C language which can perform basic tasks for us. The functionality of the Shopping Cart Although onli
11 min read
Interesting Facts About C Language C Programming language is a general purpose, case-sensitive, procedural programming language. It is one of the first and few high-level languages that is still popular among the coding community. It was developed by Dennis Ritchie and was first released in 1972. C programming language has a rich his
3 min read
Online Voting System in C Voting in elections is one of the most fundamental organs of any Democracy and in the modern world, voting is done through digital machines. In this article, we will try to write a simple Online Voting System using C programming language. Features of Online Voting System in CThe online voting system
5 min read
Amazing stuff with system() in C / C++ system() plays a very special role in executing Operating System Commands. By using this library function we can run all those terminal commands that our Operating System allows us to perform, just by using our C program. Now, we will learn a very simple code to fetch the IP Address - to identify ea
2 min read
Test Cases For Signup Page Using C Language Prerequisite: Structure in C In this article, we are going to check on how to check test cases for the signup page using C language. The signup page is where we enter data to create our account on any of the websites or applications. A test case is a document that contains various sets of data, cond
6 min read
C String Functions C language provides various built-in functions that can be used for various operations and manipulations on strings. These string functions make it easier to perform tasks such as string copy, concatenation, comparison, length, etc. The <string.h> header file contains these string functions.Th
6 min read
C Basic Syntax C is a procedural programming language. It was developed by Dennis Ritchie at the Bell Laboratories in the year 1972. Despite being old C is a very popular language among programmers. It is a very fast language compared to other languages like Python, Java, etc. Below is the basic syntax structure o
5 min read
User-Defined Function in C A user-defined function is a type of function in C language that is defined by the user himself to perform some specific task. It provides code reusability and modularity to our program. User-defined functions are different from built-in functions as their working is specified by the user and no hea
6 min read
Menu Driven Program For Vaccination Registration System Pre-Requisite: Linked list concept in C program, Function structure in C Language Problem Statement: Write a program to build a menu-driven Covid Vaccination Registration Portal using C program which can perform the following operations: Taking Candidate NamesDate, time and venue for Vaccination.Pri
6 min read