commit 9549efc60b2d6cb18190625d767d81d8ecb765d5
Author: Sirin Puenggun <sirin_29@hotmail.co.th>
Date:   Fri Jul 14 21:35:32 2023 +0700

    Add practice project

diff --git a/contact.c b/contact.c
new file mode 100644
index 0000000..a4d96cb
--- /dev/null
+++ b/contact.c
@@ -0,0 +1,132 @@
+// File : contact.c
+// Description : Implement functions defined in contact.h
+
+#include <stdio.h>
+#include <string.h>
+#include "contact.h"
+
+void addContact(Contact contacts[], int *numContacts) {
+    if (*numContacts >= MAX_CONTACTS) {
+        printf("Contact list is full.\n");
+        return;
+    }
+
+    Contact newContact;
+    printf("Enter name: ");
+    fgets(newContact.name, MAX_NAME_LENGTH, stdin);
+    newContact.name[strcspn(newContact.name, "\n")] = '\0';
+
+    printf("Enter phone number: ");
+    fgets(newContact.phone, MAX_PHONE_LENGTH, stdin);
+    newContact.phone[strcspn(newContact.phone, "\n")] = '\0';
+
+    printf("Enter email address: ");
+    fgets(newContact.email, MAX_EMAIL_LENGTH, stdin);
+    newContact.email[strcspn(newContact.email, "\n")] = '\0';
+
+    contacts[*numContacts] = newContact;
+    (*numContacts)++;
+    printf("Contact added successfully.\n");
+}
+
+void displayContacts(Contact contacts[], int numContacts) {
+    if (numContacts == 0) {
+        printf("Contact list is empty.\n");
+        return;
+    }
+
+    printf("Contacts:\n");
+    for (int i = 0; i < numContacts; i++) {
+        printf("Name: %s\n", contacts[i].name);
+        printf("Phone: %s\n", contacts[i].phone);
+        printf("Email: %s\n", contacts[i].email);
+        printf("--------------------\n");
+    }
+}
+
+void searchContacts(Contact contacts[], int numContacts, char *searchTerm) {
+    if (numContacts == 0) {
+        printf("Contact list is empty.\n");
+        return;
+    }
+
+    printf("Search results for '%s':\n", searchTerm);
+    int found = 0;
+    for (int i = 0; i < numContacts; i++) {
+        if (strstr(contacts[i].name, searchTerm) != NULL ||
+            strstr(contacts[i].phone, searchTerm) != NULL ||
+            strstr(contacts[i].email, searchTerm) != NULL) {
+            printf("Name: %s\n", contacts[i].name);
+            printf("Phone: %s\n", contacts[i].phone);
+            printf("Email: %s\n", contacts[i].email);
+            printf("--------------------\n");
+            found = 1;
+        }
+    }
+
+    if (!found) {
+        printf("No matching contacts found.\n");
+    }
+}
+
+void updateContact(Contact contacts[], int numContacts, char *searchTerm) {
+    if (numContacts == 0) {
+        printf("Contact list is empty.\n");
+        return;
+    }
+
+    int found = 0;
+    for (int i = 0; i < numContacts; i++) {
+        if (strstr(contacts[i].name, searchTerm) != NULL ||
+            strstr(contacts[i].phone, searchTerm) != NULL ||
+            strstr(contacts[i].email, searchTerm) != NULL) {
+            printf("Contact found. Enter new details:\n");
+
+            printf("Enter name: ");
+            fgets(contacts[i].name, MAX_NAME_LENGTH, stdin);
+            contacts[i].name[strcspn(contacts[i].name, "\n")] = '\0';
+
+            printf("Enter phone number: ");
+            fgets(contacts[i].phone, MAX_PHONE_LENGTH, stdin);
+            contacts[i].phone[strcspn(contacts[i].phone, "\n")] = '\0';
+
+            printf("Enter email address: ");
+            fgets(contacts[i].email, MAX_EMAIL_LENGTH, stdin);
+            contacts[i].email[strcspn(contacts[i].email, "\n")] = '\0';
+
+            printf("Contact updated successfully.\n");
+            found = 1;
+            break;
+        }
+    }
+
+    if (!found) {
+        printf("No matching contacts found.\n");
+    }
+}
+
+void deleteContact(Contact contacts[], int *numContacts, char *searchTerm) {
+    if (numContacts == 0) {
+        printf("Contact list is empty.\n");
+        return;
+    }
+
+    int found = 0;
+    for (int i = 0; i < *numContacts; i++) {
+        if (strstr(contacts[i].name, searchTerm) != NULL ||
+            strstr(contacts[i].phone, searchTerm) != NULL ||
+            strstr(contacts[i].email, searchTerm) != NULL) {
+            for (int j = i; j < *numContacts - 1; j++) {
+                contacts[j] = contacts[j + 1];
+            }
+            (*numContacts)--;
+            printf("Contact deleted successfully.\n");
+            found = 1;
+            break;
+        }
+    }
+
+    if (!found) {
+        printf("No matching contacts found.\n");
+    }
+}
diff --git a/contact.h b/contact.h
new file mode 100644
index 0000000..f14c798
--- /dev/null
+++ b/contact.h
@@ -0,0 +1,21 @@
+#ifndef CONTACT_H
+#define CONTACT_H
+
+#define MAX_NAME_LENGTH 50
+#define MAX_PHONE_LENGTH 15
+#define MAX_EMAIL_LENGTH 50
+#define MAX_CONTACTS 100
+
+typedef struct {
+    char name[MAX_NAME_LENGTH];
+    char phone[MAX_PHONE_LENGTH];
+    char email[MAX_EMAIL_LENGTH];
+} Contact;
+
+void addContact(Contact contacts[], int *numContacts);
+void displayContacts(Contact contacts[], int numContacts);
+void searchContacts(Contact contacts[], int numContacts, char *searchTerm);
+void updateContact(Contact contacts[], int numContacts, char *searchTerm);
+void deleteContact(Contact contacts[], int *numContacts, char *searchTerm);
+
+#endif
diff --git a/contact_management_system.exe b/contact_management_system.exe
new file mode 100644
index 0000000..a0f41b6
Binary files /dev/null and b/contact_management_system.exe differ
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..3c9887b
--- /dev/null
+++ b/main.c
@@ -0,0 +1,54 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "contact.h"
+#include "utils.h"
+
+int main() {
+    Contact contacts[MAX_CONTACTS];
+    int numContacts = 0;
+    int choice;
+    char searchTerm[MAX_NAME_LENGTH];
+
+    while (1) {
+        printMenu();
+        printf("Enter your choice: ");
+        scanf("%d", &choice);
+        clearInputBuffer();
+
+        switch (choice) {
+            case 1:
+                addContact(contacts, &numContacts);
+                break;
+            case 2:
+                displayContacts(contacts, numContacts);
+                break;
+            case 3:
+                printf("Enter search term: ");
+                fgets(searchTerm, MAX_NAME_LENGTH, stdin);
+                searchTerm[strcspn(searchTerm, "\n")] = '\0';
+                searchContacts(contacts, numContacts, searchTerm);
+                break;
+            case 4:
+                printf("Enter search term: ");
+                fgets(searchTerm, MAX_NAME_LENGTH, stdin);
+                searchTerm[strcspn(searchTerm, "\n")] = '\0';
+                updateContact(contacts, numContacts, searchTerm);
+                break;
+            case 5:
+                printf("Enter search term: ");
+                fgets(searchTerm, MAX_NAME_LENGTH, stdin);
+                searchTerm[strcspn(searchTerm, "\n")] = '\0';
+                deleteContact(contacts, &numContacts, searchTerm);
+                break;
+            case 6:
+                printf("Exiting program.\n");
+                exit(0);
+            default:
+                printf("Invalid choice. Please try again.\n");
+                break;
+        }
+    }
+
+    return 0;
+}
diff --git a/utils.c b/utils.c
new file mode 100644
index 0000000..7713245
--- /dev/null
+++ b/utils.c
@@ -0,0 +1,17 @@
+#include <stdio.h>
+#include "utils.h"
+
+void clearInputBuffer() {
+    int c;
+    while ((c = getchar()) != '\n' && c != EOF) {}
+}
+
+void printMenu() {
+    printf("\nContact Management System\n");
+    printf("1. Add contact\n");
+    printf("2. Display all contacts\n");
+    printf("3. Search contact\n");
+    printf("4. Update contact\n");
+    printf("5. Delete contact\n");
+    printf("6. Exit\n");
+}
diff --git a/utils.h b/utils.h
new file mode 100644
index 0000000..b39a8b3
--- /dev/null
+++ b/utils.h
@@ -0,0 +1,9 @@
+#ifndef UTILS_H
+#define UTILS_H
+
+#define MAX_CONTACTS 100
+
+void clearInputBuffer();
+void printMenu();
+
+#endif