feat: implement Library Management System in C++ using OOP principles

Src/Library_Managment/LibraryManagement.cpp

@@ -0,0 +1,230 @@
+#include "LibraryManagement.h"
+
+// ------------ helpers ------------
+static inline string trim(const string &s) {
+    size_t a = s.find_first_not_of(" \t\r\n");
+    if (a == string::npos) return "";
+    size_t b = s.find_last_not_of(" \t\r\n");
+    return s.substr(a, b - a + 1);
+}
+
+static inline string lower(const string &s) {
+    string t = s;
+    transform(t.begin(), t.end(), t.begin(), ::tolower);
+    return t;
+}
+
+// ------------ Book ------------
+Book::Book() : id(-1), totalCopies(0), availableCopies(0) {}
+Book::Book(int i, string t, string a, string c, int copies)
+    : id(i), title(move(t)), author(move(a)), category(move(c)),
+      totalCopies(copies), availableCopies(copies) {}
+
+int Book::getId() const { return id; }
+string Book::getTitle() const { return title; }
+string Book::getAuthor() const { return author; }
+string Book::getCategory() const { return category; }
+int Book::getTotalCopies() const { return totalCopies; }
+int Book::getAvailableCopies() const { return availableCopies; }
+
+void Book::setTitle(const string &t) { title = t; }
+void Book::setAuthor(const string &a) { author = a; }
+void Book::setCategory(const string &c) { category = c; }
+void Book::setTotalCopies(int c) {
+    if (c < 0) throw runtime_error("Total copies cannot be negative");
+    int issued = totalCopies - availableCopies;
+    if (c < issued) throw runtime_error("Cannot set total copies less than already issued copies");
+    totalCopies = c;
+    availableCopies = c - issued;
+}
+
+bool Book::issueOne() {
+    if (availableCopies <= 0) return false;
+    --availableCopies;
+    return true;
+}
+
+bool Book::returnOne() {
+    if (availableCopies >= totalCopies) return false;
+    ++availableCopies;
+    return true;
+}
+
+string Book::toCSV() const {
+    return to_string(id) + "," + title + "," + author + "," + category + "," +
+           to_string(totalCopies) + "," + to_string(availableCopies);
+}
+
+Book Book::fromCSV(const string &line) {
+    stringstream ss(line);
+    string id, t, a, c, total, avail;
+    getline(ss, id, ',');
+    getline(ss, t, ',');
+    getline(ss, a, ',');
+    getline(ss, c, ',');
+    getline(ss, total, ',');
+    getline(ss, avail, ',');
+    Book b;
+    b = Book(stoi(id), trim(t), trim(a), trim(c), stoi(total));
+    b.setTotalCopies(stoi(total));
+    while (b.getAvailableCopies() > stoi(avail)) b.issueOne();
+    return b;
+}
+
+// ------------ Member ------------
+Member::Member() : id(-1) {}
+Member::Member(int i, string n, string e) : id(i), name(move(n)), email(move(e)) {}
+
+int Member::getId() const { return id; }
+string Member::getName() const { return name; }
+string Member::getEmail() const { return email; }
+
+void Member::setName(const string &n) { name = n; }
+void Member::setEmail(const string &e) { email = e; }
+
+string Member::toCSV() const { return to_string(id) + "," + name + "," + email; }
+
+Member Member::fromCSV(const string &line) {
+    stringstream ss(line);
+    string id, n, e;
+    getline(ss, id, ',');
+    getline(ss, n, ',');
+    getline(ss, e, ',');
+    return Member(stoi(id), trim(n), trim(e));
+}
+
+// ------------ Library ------------
+Library::Library() { loadAll(); }
+Library::~Library() { saveAll(); }
+
+void Library::loadAll() {
+    ifstream fb(booksFile);
+    if (fb) {
+        string line;
+        while (getline(fb, line))
+            if (!trim(line).empty()) {
+                Book b = Book::fromCSV(line);
+                books[b.getId()] = b;
+                nextBookId = max(nextBookId, b.getId() + 1);
+            }
+    }
+
+    ifstream fm(membersFile);
+    if (fm) {
+        string line;
+        while (getline(fm, line))
+            if (!trim(line).empty()) {
+                Member m = Member::fromCSV(line);
+                members[m.getId()] = m;
+                nextMemberId = max(nextMemberId, m.getId() + 1);
+            }
+    }
+}
+
+void Library::saveAll() {
+    ofstream fb(booksFile);
+    for (auto &[_, b] : books)
+        fb << b.toCSV() << "\n";
+
+    ofstream fm(membersFile);
+    for (auto &[_, m] : members)
+        fm << m.toCSV() << "\n";
+}
+
+// Books
+int Library::addBook(const string &t, const string &a, const string &c, int copies) {
+    int id = nextBookId++;
+    books[id] = Book(id, t, a, c, copies);
+    return id;
+}
+
+void Library::updateBook(int id, const optional<string> &t, const optional<string> &a,
+                         const optional<string> &c, const optional<int> &copies) {
+    auto it = books.find(id);
+    if (it == books.end()) throw runtime_error("Book not found");
+    if (t) it->second.setTitle(*t);
+    if (a) it->second.setAuthor(*a);
+    if (c) it->second.setCategory(*c);
+    if (copies) it->second.setTotalCopies(*copies);
+}
+
+void Library::deleteBook(int id) {
+    if (!books.count(id)) throw runtime_error("Book not found");
+    books.erase(id);
+}
+
+vector<Book> Library::listBooks() const {
+    vector<Book> v;
+    for (auto &[_, b] : books) v.push_back(b);
+    sort(v.begin(), v.end(), [](auto &x, auto &y){return x.getId()<y.getId();});
+    return v;
+}
+
+vector<Book> Library::searchByTitle(const string &q) const {
+    vector<Book> r;
+    for (auto &[_, b] : books)
+        if (lower(b.getTitle()).find(lower(q)) != string::npos)
+            r.push_back(b);
+    return r;
+}
+
+vector<Book> Library::searchByAuthor(const string &q) const {
+    vector<Book> r;
+    for (auto &[_, b] : books)
+        if (lower(b.getAuthor()).find(lower(q)) != string::npos)
+            r.push_back(b);
+    return r;
+}
+
+vector<Book> Library::searchByCategory(const string &q) const {
+    vector<Book> r;
+    for (auto &[_, b] : books)
+        if (lower(b.getCategory()).find(lower(q)) != string::npos)
+            r.push_back(b);
+    return r;
+}
+
+// Members
+int Library::addMember(const string &n, const string &e) {
+    int id = nextMemberId++;
+    members[id] = Member(id, n, e);
+    return id;
+}
+
+void Library::updateMember(int id, const optional<string>& n, const optional<string>& e) {
+    auto it = members.find(id);
+    if (it == members.end()) throw runtime_error("Member not found");
+    if (n) it->second.setName(*n);
+    if (e) it->second.setEmail(*e);
+}
+
+void Library::deleteMember(int id) {
+    if (!members.count(id)) throw runtime_error("Member not found");
+    members.erase(id);
+}
+
+vector<Member> Library::listMembers() const {
+    vector<Member> v;
+    for (auto &[_, m] : members) v.push_back(m);
+    sort(v.begin(), v.end(), [](auto &x, auto &y){return x.getId()<y.getId();});
+    return v;
+}
+
+// Transactions
+void Library::issueBook(int memberId, int bookId) {
+    if (!members.count(memberId)) throw runtime_error("Invalid member");
+    if (!books.count(bookId)) throw runtime_error("Invalid book");
+    if (!books[bookId].issueOne()) throw runtime_error("No available copies");
+    transactions.push_back({memberId, bookId, "2025-10-23", false});
+}
+
+void Library::returnBook(int memberId, int bookId) {
+    if (!members.count(memberId)) throw runtime_error("Invalid member");
+    if (!books.count(bookId)) throw runtime_error("Invalid book");
+    books[bookId].returnOne();
+    for (auto &tx : transactions)
+        if (tx.memberId == memberId && tx.bookId == bookId && !tx.returned) {
+            tx.returned = true;
+            return;
+        }
+}

Src/Library_Managment/LibraryManagement.h

@@ -0,0 +1,104 @@
+#ifndef LIBRARYMANAGEMENT_H
+#define LIBRARYMANAGEMENT_H
+
+#include <bits/stdc++.h>
+using namespace std;
+
+// ---------------- Book ----------------
+class Book {
+    int id;
+    string title, author, category;
+    int totalCopies, availableCopies;
+
+public:
+    Book();
+    Book(int id, string title, string author, string category, int copies);
+
+    int getId() const;
+    string getTitle() const;
+    string getAuthor() const;
+    string getCategory() const;
+    int getTotalCopies() const;
+    int getAvailableCopies() const;
+
+    void setTitle(const string&);
+    void setAuthor(const string&);
+    void setCategory(const string&);
+    void setTotalCopies(int);
+
+    bool issueOne();
+    bool returnOne();
+
+    string toCSV() const;
+    static Book fromCSV(const string&);
+};
+
+// ---------------- Member ----------------
+class Member {
+    int id;
+    string name, email;
+
+public:
+    Member();
+    Member(int id, string name, string email);
+
+    int getId() const;
+    string getName() const;
+    string getEmail() const;
+
+    void setName(const string&);
+    void setEmail(const string&);
+
+    string toCSV() const;
+    static Member fromCSV(const string&);
+};
+
+// ---------------- Transaction ----------------
+struct Transaction {
+    int memberId;
+    int bookId;
+    string date;
+    bool returned;
+};
+
+// ---------------- Library ----------------
+class Library {
+    unordered_map<int, Book> books;
+    unordered_map<int, Member> members;
+    vector<Transaction> transactions;
+
+    int nextBookId = 1;
+    int nextMemberId = 1;
+
+    const string booksFile = "books.csv";
+    const string membersFile = "members.csv";
+    const string txFile = "transactions.csv";
+
+    void loadAll();
+    void saveAll();
+
+public:
+    Library();
+    ~Library();
+
+    // Books
+    int addBook(const string&, const string&, const string&, int);
+    void updateBook(int, const optional<string>&, const optional<string>&, const optional<string>&, const optional<int>&);
+    void deleteBook(int);
+    vector<Book> listBooks() const;
+    vector<Book> searchByTitle(const string&) const;
+    vector<Book> searchByAuthor(const string&) const;
+    vector<Book> searchByCategory(const string&) const;
+
+    // Members
+    int addMember(const string&, const string&);
+    void updateMember(int, const optional<string>&, const optional<string>&);
+    void deleteMember(int);
+    vector<Member> listMembers() const;
+
+    // Transactions
+    void issueBook(int memberId, int bookId);
+    void returnBook(int memberId, int bookId);
+};
+
+#endif