`std::unique_ptr`¶

A std::unique_ptr<T> provides exclusive ownership of a dynamically allocated resource. Only one unique_ptr can own a given object at a time.

Basics¶

#include <iostream>
#include <memory>

int main() {
    auto p = std::make_unique<int>(42);  // creates and owns an int
    std::cout << *p << '\n';             // access value

    auto q = std::move(p);               // transfer ownership
    if (!p) std::cout << "p is null\n";  // p no longer owns the resource
}

Rules of Thumb¶

Ownership is unique — cannot be copied, only moved.
Resource is automatically destroyed when the last unique_ptr owning it is destroyed.
Use std::make_unique<T>() instead of new for exception safety.
get() returns a non-owning raw pointer for observation.
reset() releases ownership (optionally replaces it with another resource).

Use Cases¶

Representing exclusive ownership of resources.
Managing dynamic allocations within classes (RAII pattern).
Avoiding leaks when exceptions occur.
Safely returning dynamically allocated objects from functions.

Example¶

std::unique_ptr<int> create_value() {
    return std::make_unique<int>(10);
}

int main() {
    auto value = create_value();
    std::cout << *value << '\n';
}