#include<iostream>
using namespace std;void main2()
{int *p1 = new int(4);//指向一个变量int *p2 = new int[10]{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };//指向数组delete p1;//delete p1    int *p1 = new int(4);delete[] p2;//delete[] p2  int *p2 = new int[10]{ 1,2,3,4,5,6,7,8,9,0 };
    cin.get();
}
//数组new和初始化
void main3()
{int *p = new int[10]{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };cout << p << endl;cout << "--------------" << endl;delete[] p;cin.get();
}

//基本数据类型new及初始化
void main4()
{int *p1 = new int(4);cout << p1 << endl;cout << "--------------" << endl;delete p1;//delete[] p1;cin.get();
}
class mydata
{
public:mydata() //构造函数
    {cout << "create" << endl;}~mydata()//析构函数
    {cout << "delete" << endl;}
};void main()
{mydata *p(new mydata);delete p;//mydata *p(new mydata);//delete []p;//单个堆上的对象，不可以 delete [],反复deletemydata *p(new mydata[10]);delete  []p;//异常cin.get();
}

#include <iostream>
#include <new>using namespace std;const int BUF = 512;
const int N = 5;
char buffer[BUF];int main()
{double *p1, *p2;cout << "calling new and placement new " << endl;p1 = new double[N];p2 = new (buffer) double[N];for (int i = 0; i < N; i++){p2[i] = p1[i] = 1000 + 10.0*i;}cout << "heap:"<<p1<< "      static:"<<(void*)buffer << endl;cout << "memory contents:" << endl;for (int i = 0; i < N;i++){cout <<" p1  "<< p1[i] << " at " << &p1[i] << ";   ";cout << " p2  "<<p2[i] << " at " << &p2[i] << endl;}cout << "   " << endl;cout << "calling new and placement new a second time" << endl;double *p3, *p4;p3 = new double[N];p4 = new (buffer) double[N];//重写数据for (int i = 0; i < N; i++){p4[i] = p3[i] = 1000 + 50.0*i;}cout << "memory contents:" << endl;for (int i = 0; i < N; i++){cout << "p3  "<<p3[i] << " at " << &p3[i] << ";   ";cout << "p4  " << p4[i] << " at " << &p4[i] << endl;}cout << "   " << endl;cout << "calling new and placement new a third time" << endl;delete [] p1;p1 = new double[N];p2 = new(buffer + N*sizeof(double)) double[N];for (int i = 0; i < N; i++){p2[i] = p1[i] = 1000 + 70.0*i;}cout << "memory contents:" << endl;for (int i = 0; i < N; i++){cout <<"p1 "<< p1[i] << " at " << &p1[i] << ";   ";cout << "p2"<<p2[i] << " at " << &p2[i] << endl;}delete[]p1;delete[]p3;cin.get();return 0;
}

运行结果：

calling new and placement new
heap:007AB2F8      static:01380320
memory contents:p1  1000 at 007AB2F8;    p2  1000 at 01380320p1  1010 at 007AB300;    p2  1010 at 01380328p1  1020 at 007AB308;    p2  1020 at 01380330p1  1030 at 007AB310;    p2  1030 at 01380338p1  1040 at 007AB318;    p2  1040 at 01380340calling new and placement new a second time
memory contents:
p3  1000 at 007AB500;   p4  1000 at 01380320
p3  1050 at 007AB508;   p4  1050 at 01380328
p3  1100 at 007AB510;   p4  1100 at 01380330
p3  1150 at 007AB518;   p4  1150 at 01380338
p3  1200 at 007AB520;   p4  1200 at 01380340calling new and placement new a third time
memory contents:
p1 1000 at 007AB2F8;   p21000 at 01380348
p1 1070 at 007AB300;   p21070 at 01380350
p1 1140 at 007AB308;   p21140 at 01380358
p1 1210 at 007AB310;   p21210 at 01380360
p1 1280 at 007AB318;   p21280 at 01380368

定位new运算符，将p2放在了数组buffer中，p2和buffer的地址都是01380320；然而他们的类型不同，p2是double的指针，buffer是char的指针。所以用void*对buffer进行类型转换，不然buffer打印出来的是一个字符。

最后，不能直接delete [  ] p2，由于buffer指定的是内存的静态内存，而delete只能释放堆区的分配的内存。