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Smart pointer 智能指针小总结

2024-09-30 19:53:02   216人阅读

Smart pointer

 line 58之后smart pointer里的计数已经是0，所以会真正释放它引用的对象，调用被引用对象的析构函数。如果继续用指针访问，会出现如下图的内存访问异常。所以说如果选择了用智能指针，就不要再试图用其他方式再去访问对象了。

 

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 1 // sharedTest.cpp : Defines the entry point for the console application. 2 // 3  4 #include "stdafx.h" 5 #include <boost/make_shared.hpp> 6 #include <vector> 7 //using namespace std; 8 using namespace boost; 9 10 #define SMART_PTR shared_ptr 11 12 class Based13 {14 protected:15     int a;16     char* pa;17 18 public:19     Based():a(0)20     {21         pa = new char[10];22     }23 24     void Func(){ std::cout<<"Func "<<a<<std::endl; }25     virtual ~Based()26     {27         delete[] pa;28         std::cout<<"deconstrctor"<<std::endl;29     }30 };31 32 33 34 class Foo : public Based35 {36 private:37     int b;38 39 public:40     void Test()41     { 42         this->b = 100;43         this->pa[0] = ‘b‘;44         std::cout<<"Test(), b = "<<this->b<<"this->pa[0] =  "<<this->pa[0]<<std::endl;45     }46 47     ~Foo(){ std::cout<<"~Foo()"<<std::endl;}48 };49 50 int main (int argc, const char * argv[])51 {52     Foo * pfoo = new Foo;53 54     std::cout<<"{"<<std::endl;55     {56       SMART_PTR<Foo> smart_foo(pfoo);57       smart_foo->Test();58     }59     std::cout<<"}"<<std::endl;60 61     pfoo->Test();62 63     return 1;64 }

 

 

 

 

Smart pointer 智能指针小总结


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