编辑“︁C++ shared ptr 详解”︁（章节）

=== 引用计数机制 ===
可以通过 `use_count()` 方法查看当前引用计数：
<syntaxhighlight lang="cpp">
#include <memory>
#include <iostream>

void showCount(std::shared_ptr<int> p) {
    std::cout << "count: " << p.use_count() << std::endl;
}

int main() {
    auto p = std::make_shared<int>(10);
    std::cout << "count after creation: " << p.use_count() << std::endl; // 1
    
    {
        auto p2 = p;
        std::cout << "count after copy: " << p.use_count() << std::endl; // 2
        showCount(p); // 函数内会再创建一个拷贝，count: 3
    }
    
    std::cout << "count after scope: " << p.use_count() << std::endl; // 1
    return 0;
}
</syntaxhighlight>
'''输出'''：
<pre>
count after creation: 1
count after copy: 2
count: 3
count after scope: 1
</pre>