std::shared_ptr（C++11）

In a Nutshell

Multiple smart pointers can jointly own the same object; the object is automatically released only when the last owner is destroyed or reset.

Header

#include <memory>

Core API Quick Reference

Operation	Signature	Description
Construction	shared_ptr()	Constructs a null pointer (default)
Construction (factory)	template<class T, class... Args> shared_ptr<T> make_shared(Args&&... args)	Allocates and constructs an object (C++11)
Reset	void reset()	Releases ownership of the currently managed object
Get raw pointer	T* get() const noexcept	Returns the stored pointer
Dereference	T& operator*() const noexcept	Dereferences the stored pointer
Arrow operator	T* operator->() const noexcept	Access members through the pointer
Reference count	long use_count() const noexcept	Returns the number of shared_ptrs sharing the object
Boolean conversion	explicit operator bool() const noexcept	Checks if it manages a non-null object
Swap	void swap(shared_ptr& r) noexcept	Swaps the managed objects of two shared_ptrs

Minimal Example

#include <iostream>
#include <memory>
struct Foo { Foo() { std::cout << "Foo()\n"; } ~Foo() { std::cout << "~Foo()\n"; } };
int main() {
    std::shared_ptr<Foo> p1 = std::make_shared<Foo>();
    std::shared_ptr<Foo> p2 = p1; // 引用计数变为 2
    std::cout << "count: " << p1.use_count() << "\n";
    p1.reset(); // count: 1
    p2.reset(); // 析构 Foo
}

Embedded Applicability: Medium

• Internally maintains a control block and atomic reference count, incurring extra memory and CPU overhead
• Copy operations are inherently thread-safe, making it suitable for sharing resources across tasks
• Use with caution on MCUs with extremely limited RAM and Flash; prefer unique_ptr

Compiler Support

GCC	Clang	MSVC
TBD	TBD	TBD

See Also

• cppreference: std::shared_ptr

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