C++ Day 33

  C++ Day 33: Smart Pointers & Memory Management

🔹 1. wherefore forward pointers

in c++ hand-operated green / cancel is error-prone:

memory leaks 🧠

double deletes ❌

dangling pointers 💥

smart pointers care store mechanically exploitation raii (Supply skill is initialization)

🔹 ii. Types of Smart Pointers in C++

✅ std::unique_ptr

Sole ownership of a Supply.

Cannot be copied.

Automatically deletes the Supply when it goes out of scope.

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#include 

unique_ptr ptr1 = make_unique(10);

cout << *ptr1 << endl; // 10

You can transfer ownership:

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unique_ptr ptr2 = move(ptr1);

✅ std::shared_ptr

Shared ownership multiple shared_ptrs can point to the same object.

Uses reference counting to track how many owners.

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shared_ptr p1 = make_shared(100);

shared_ptr p2 = p1;  // Reference count = 2

When count goes to 0 memory is released.

✅ std::weak_ptr

Non-owning reference to a shared_ptr-managed object.

Used to break cyclic references (e.g. in graphs or linked structures).

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shared_ptr sp = make_shared(50);

weak_ptr wp = sp;

if (auto temp = wp.lock()) {

    cout << *temp << endl;

}

🔹 3. bespoke deleters

you get delineate however amp forward arrow need cancel its object

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unique_ptr file(fopen("Checktxt" "r") &fclose);

🔹 cardinal. Common Mistakes

Using raw pointers where smart pointers are better.

Creating cyclic references with shared_ptr.

Forgetting move() with unique_ptr.

🔹 5. compare table

Characteristic unique_ptr shared_ptr weak_ptr

ownership exclusive shared non-owning

copyable ❌ ✅ ✅

reference cnt ❌ ✅ ✅ (uses weak)

use case single owner multiple use avoid cycles

🧪 do task:

Make amp family hold and care amp active range of hold objects exploitation shared_ptr. Add a method to show the reference count of a particular Book.

✅ Summary:

Smart pointers = safer dynamic memory

Use make_unique / make_shared instead of new

Prefer unique_ptr by default shared_ptr when needed