动态内存申请的结果

Posted 2021-10-08 学习只为旅行

#include <iostream>
#include <new>
#include <cstdlib>
#include <exception>

using namespace std;

class Test
{
    int m_value;
public:
    Test()
    {
        cout << "Test()" << endl;
        
        m_value = 0;
    }
    
    ~Test()
    {
        cout << "~Test()" << endl;  
    }
    
    void* operator new (unsigned int size) throw()
    {
        cout << "operator new: " << size << endl;
        
        // return malloc(size);
        
        return NULL;
    }
    
    void operator delete (void* p)
    {
        cout << "operator delete: " << p << endl;
        
        free(p);
    }
    
    void* operator new[] (unsigned int size) throw()
    {
        cout << "operator new[]: " << size << endl;
        
        // return malloc(size);
        
        return NULL;
    }
    
    void operator delete[] (void* p)
    {
        cout << "operator delete[]: " << p << endl;
        
        free(p);
    }
};

void my_new_handler()
{
    cout << "void my_new_handler()" << endl;
}

void ex_func_1()
{
    new_handler func = set_new_handler(my_new_handler);
    
    try
    {
        cout << "func = " << func << endl;
        
        if( func )
        {
            func();
        }
    }
    catch(const bad_alloc&)
    {
        cout << "catch(const bad_alloc&)" << endl;
    }
}

void ex_func_2()
{
    Test* pt = new Test();
    
    cout << "pt = " << pt << endl;
    
    delete pt;
    
    pt = new Test[5];
    
    cout << "pt = " << pt << endl;
    
    delete[] pt; 
}

void ex_func_3()
{
    int* p = new(nothrow) int[10];
    
    // ... ...
    
    delete[] p; 
    
    int bb[2] = {0};
    
    struct ST
    {
        int x;
        int y;
    };
    
    ST* pt = new(bb) ST();
    
    pt->x = 1;
    pt->y = 2;
    
    cout << bb[0] << endl;
    cout << bb[1] << endl;
    
    pt->~ST();
}

int main(int argc, char *argv[])
{
    // ex_func_1();
    // ex_func_2();
    // ex_func_3();
    
    return 0;
}

func1:

func2：

func3:

小结