unit 5 opps

 

1️⃣ Strings in C++

🔹 Definition (Easy Words)

A string is a collection of characters used to store text like name, address, etc.

Example:

• "Ujjwal"

• "ATM Machine"

• "Library Book"

---

🔹 String in C++

C++ provides string class in <string> library.

#include <iostream>
#include <string>
using namespace std;

int main() {
    string name = "Ujjwal";
    cout << name;
}

---

🔹 Common String Operations

string s1 = "Hello";
string s2 = "World";

cout << s1 + " " + s2;   // Concatenation
cout << s1.length();     // Length

---

2️⃣ Exception Handling in C++

🔹 Definition (Easy Words)

Exception handling is a method to handle errors during program execution so the program does not crash.

In simple words:
👉 If an error happens, we handle it safely.

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🔹 Keywords Used

• try

• catch

• throw

---

🔹 Example

#include <iostream>
using namespace std;

int main() {
    int a = 10, b = 0;

    try {
        if (b == 0)
            throw "Division by zero not allowed";
        cout << a / b;
    }
    catch (const char* msg) {
        cout << msg;
    }
}

Here:
If error happens → program shows message instead of crashing.

---

3️⃣ Introduction to Multithreading

🔹 Definition (Easy Words)

Multithreading means running multiple tasks at the same time in a program.

Example:

• ATM processing multiple users

• Browser downloading and playing video together

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🔹 Thread in C++

C++ provides <thread> library.

#include <iostream>
#include <thread>
using namespace std;

void display() {
    cout << "Thread running\n";
}

int main() {
    thread t1(display);
    t1.join();
}

---

🔹 Why Multithreading?

✅ Faster execution
✅ Better CPU usage
✅ Performs multiple tasks together

---

4️⃣ Data Collections in C++

🔹 Definition (Easy Words)

Data collection means storing multiple data items together.

C++ provides STL (Standard Template Library):

• Vector

• List

• Map

• Set

---

🔹 Example: Vector

#include <iostream>
#include <vector>
using namespace std;

int main() {
    vector<int> numbers = {10, 20, 30};

    for (int n : numbers) {
        cout << n << " ";
    }
}

---

🔹 Example: Map

#include <map>
#include <iostream>
using namespace std;

int main() {
    map<int, string> student;
    student[1] = "Ujjwal";
    student[2] = "Rahul";

    cout << student[1];
}

---

5️⃣ Case Study 1: ATM System (Using OOP Concepts)

🔹 Classes Required

• Account

• ATM

• User

---

🔹 Simple ATM Example

#include <iostream>
using namespace std;

class ATM {
private:
    double balance;

public:
    ATM(double b) {
        balance = b;
    }

    void withdraw(double amount) {
        try {
            if (amount > balance)
                throw "Insufficient Balance";
            balance -= amount;
            cout << "Withdraw Successful\n";
        }
        catch (const char* msg) {
            cout << msg << endl;
        }
    }

    void checkBalance() {
        cout << "Balance: " << balance << endl;
    }
};

int main() {
    ATM user1(5000);
    user1.withdraw(6000);
    user1.checkBalance();
}

Concepts Used:

✅ Encapsulation
✅ Exception Handling
✅ Strings
✅ OOP

---

6️⃣ Case Study 2: Library Management System

🔹 Classes Required

• Book

• Student

• Library

---

🔹 Example

#include <iostream>
#include <vector>
using namespace std;

class Book {
public:
    string title;
    bool issued;

    Book(string t) {
        title = t;
        issued = false;
    }
};

class Library {
private:
    vector<Book> books;

public:
    void addBook(string title) {
        books.push_back(Book(title));
    }

    void showBooks() {
        for (Book b : books) {
            cout << b.title << endl;
        }
    }
};

int main() {
    Library lib;
    lib.addBook("C++ Programming");
    lib.addBook("Data Structures");
    lib.showBooks();
}

Concepts Used:

✅ Strings
✅ Data Collections (vector)
✅ OOP
✅ Objects and Classes

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7️⃣ Quick Revision Table

Topic	Simple Meaning
String	Text storage
Exception Handling	Handling errors safely
Multithreading	Running tasks at same time
Data Collection	Storing multiple data together
ATM Case Study	Real-world banking system
Library Case Study	Book management system