#include
        
         #include 
         
          using namespace std;int main(){    /**     * 动态内存     * url: http://www.cplusplus.com/doc/tutorial/dynamic/     * 关键字new用于在程序运行时动态开辟内存,内存开辟在堆空间.     * 此关键字不保证内存一定开辟成功,如果开辟失败,抛出bad_alloc异常,如果此异常没有指定的异常handle,程序就会终止.     */    int * foo = nullptr;    foo = new int[5];  // if allocation fails, an exception is thrown    //另一个方法是nothrow,使用此方法,内存开辟失败,返回null,而不是抛出异常让程序终止    //此方法声明在new文件头内    foo = new (std::nothrow) int[5];    if(foo == nullptr)    {    }    else    {        foo[0] = 1;        cout << foo[0] << endl;        delete[] foo;    }    //内存不在使用,删除内存,delete    int i, n;    int *p;    cout << "how many numbers would you like to type?\n";    cin >> i;    cout << "i=" << i << endl;    p = new (std::nothrow) int[i];    if(p == nullptr)    {        cout << "Error: memory could not be allocated" << endl;    }    else    {        for(n = 0; n < i; n++)        {            cout << "enter number:";            cin >> p[n];        }        cout << "you have enter:";        for(n = 0; n < i; n++)            cout << p[n] << ", ";        delete[] p;    }    return 0;}