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  • 走进C++程序世界-----operator new delete 重载

     在C++ 的世界里,new 和delete 是keyword。而在C的世界里相相应的malloc和free是函数,关键C++的new和delete分析,详见前面的章节。这里就不在过多的介绍了。链接

    以下来研究下关于new 和delete的重载。

     1、对照使用重载和未使用重载

     未使用“

    /*File : operator_new.cpp
     *Auth : sjin
     *Date : 2014-04-27
     *Mail : 413977243@qq.com
     */
    
    #include <iostream>
    
    using namespace std;
    
    class test {
    public:
    	test(){cout << "*****构造test()*****"<< endl;};
    	~test(){cout << "+++++析构test()+++++"<< endl;};
    };
    
    int main()
    {
    	test * x = new test;//运行分配空间,再运行析构函数
    	delete x;//先运行析构函数,在释放空间
    }

    使用重载后,

    /*File : operator_new.cpp
     *Auth : sjin
     *Date : 2014-04-27
     *Mail : 413977243@qq.com
     */
    
    #include <iostream>
    
    using namespace std;
    
    char mem[10000] = {''};
    int pos = 0;
    
    class test {
    public:
    	test(){cout << "*****构造test()*****"<< endl;};
    	~test(){cout << "+++++析构test()+++++"<< endl;};
    
    public:
    	void * operator new(size_t bytes){
    		cout << "------new test()------" << endl;
    		int alloc = pos;
    		pos += bytes;
    		return (mem + alloc);
    	};
    
    	void operator delete(void *){
    		cout << "------delete test()------" << endl;
    
    	};
    };
    
    int main()
    {
    	test * x = new test;
    
    	delete x;
    }


    /*File : operator_new.cpp
     *Auth : sjin
     *Date : 2014-04-27
     *Mail : 413977243@qq.com
     */
    
    #include <iostream>
    
    using namespace std;
    
    char mem[10000] = {''};
    int pos = 0;
    
    class test {
    public:
    	test(){cout << "*****构造test()*****"<< endl;};
    	~test(){cout << "+++++析构test()+++++"<< endl;};
    
    public:
    	void * operator new(size_t bytes){
    		cout << "------new test()------" << endl;
    		int alloc = pos;
    		pos += bytes;
    		return (mem + alloc);
    	};
    
    	void operator delete(void *){
    		cout << "------delete test()------" << endl;
    
    	};
    };
    
    int main()
    {
    	test * x = new test;
    
    	delete x;
    
    	x = new test[3];
    
    	delete [] x;//这里对数组释放,须要注意
    }


    #include <iostream>
    
    using namespace std;
    
    char mem[10000] = {''};
    int pos = 0;
    
    class test {
    public:
    	test(){cout << "*****构造test()*****"<< endl;};
    	~test(){cout << "+++++析构test()+++++"<< endl;};
    
    public:
    	void * operator new(size_t bytes){
    		cout << "------new test()------" << endl;
    		int alloc = pos;
    		pos += bytes;
    		return (mem + alloc);
    	};
    
    	void operator delete(void *){
    		cout << "------delete test()------" << endl;
    
    	};
    
    	void * operator new[](size_t bytes){
    		cout << "------new test()------" << endl;
    		int alloc = pos;
    		pos += bytes;
    		return (mem + alloc);
    	};
    
    	void operator delete[](void *){
    		cout << "------delete test()------" << endl;
    
    	};
    };
    
    int main()
    {
    	test * x = new test;
    
    	delete x;
    
    	x = new test[3];
    
    	delete [] x;
    }


    对new 和delete 函数的重载能够用来检測 内存泄露的情况。



     










     


     


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  • 原文地址:https://www.cnblogs.com/zhchoutai/p/8685569.html
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