std::unique_ptr (C++11)

In a Nutshell

A smart pointer that manages the lifetime of dynamic objects through exclusive ownership semantics: it destroys the object automatically when it goes out of scope, and it is exactly the same size as a raw pointer.

Header

#include <memory>

Core API Cheat Sheet

Operation	Signature	Description
Create object	template<class T> unique_ptr<T> make_unique(Args&&... args)	(C++14) Creates a unique_ptr in an exception-safe manner
Constructor	constexpr unique_ptr(pointer p = pointer())	Takes over a raw pointer
Destructor	~unique_ptr()	Destroys the managed object
Release ownership	pointer release() noexcept	Relinquishes ownership and returns the raw pointer
Reset pointer	void reset(pointer p = pointer())	Destroys the current object and takes over a new pointer
Get raw pointer	pointer get() const noexcept	Returns the managed raw pointer
Check if empty	explicit operator bool() const noexcept	Tests whether it holds an object
Dereference	T& operator*() const	Accesses the managed object
Member access	T* operator->() const	Accesses members through the pointer
Array subscript	T& operator[](size_t i) const	(Array specialization) Accesses array elements

Minimal Example

// Standard: C++14
#include <iostream>
#include <memory>
struct Foo { ~Foo() { std::cout << "destroyed\n"; } };
int main() {
    std::unique_ptr<Foo> p = std::make_unique<Foo>();
    std::unique_ptr<Foo> q = std::move(p); // Transfers ownership
    std::cout << std::boolalpha << (p == nullptr) << "\n"; // true
} // "destroyed"

Embedded Applicability: High

• Zero-overhead abstraction: compiles to the same size as a raw pointer, with no extra memory footprint
• Deterministic destruction: releases immediately at end of scope, matching embedded demands for real-time behavior and deterministic memory usage
• Fully supports the pImpl idiom, hiding implementation details and shortening compilation dependency chains
• Introduces no control block, avoiding the thread-safety and memory-fragmentation overhead of shared_ptr

Compiler Support

GCC	Clang	MSVC
4.4	2.9	2010

See Also

• cppreference: std::unique_ptr

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