std::unique_ptr (C++11)

In a nutshell

A smart pointer that manages the lifecycle of dynamic objects via exclusive ownership semantics. It automatically destroys the object when it goes out of scope, and its size is identical to that of 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) Create unique_ptr in an exception-safe manner
Constructor	constexpr unique_ptr(pointer p = pointer())	Take ownership of a raw pointer
Destructor	~unique_ptr()	Destroy the managed object
Release ownership	pointer release() noexcept	Relinquish ownership and return the raw pointer
Reset pointer	void reset(pointer p = pointer())	Destroy current object and take ownership of a new pointer
Get raw pointer	pointer get() const noexcept	Return the managed raw pointer
Check if empty	explicit operator bool() const noexcept	Determine if an object is held
Dereference	T& operator*() const	Access the managed object
Member access	T* operator->() const	Access members via pointer
Array subscript	T& operator[](size_t i) const	(Array specialization) Access 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); // 转移所有权
    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 additional memory overhead.
• Deterministic destruction: Releases memory immediately when the scope ends, aligning with embedded requirements for real-time performance and deterministic memory usage.
• Perfectly supports the pImpl idiom, allowing implementation details to be hidden 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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