指针与自由存储空间

long * fellow; // create a pointer-to-long
*fellow = 223323; // place a value in never-never land

int * pn = new int;

typeName * pointer_name = new typeName;

// use_new.cpp -- using the new operator
#include 
int main()
{
    using namespace std;
    int nights = 1001;
    int * pt = new int;  // allocate space for an int
    *pt = 1001;          // store a value there

    cout << "nights value = ";
    cout << nights << ": location " << &nights << endl;
    cout << "int ";
    cout << "value = " << *pt << ": location = " << pt << endl;
    double * pd = new double; // allocate space for a double
    *pd = 10000001.0; // store a double there

    cout << "double ";
    cout << "value = " << *pd << ": location = " << pd << endl;
    cout << "location of pointer pd: " << &pd << endl;
    cout << "size of pt = " << sizeof(pt);
    cout << ": size of *pt = " << sizeof(*pt) << endl;
    cout << "size of pd = " << sizeof pd;
    cout << ": size of *pd = " << sizeof(*pd) << endl;
    return 0;
}

nights value = 1001: location 0028F7F8
int value = 1001: location = 00033A98
double value = 1e+007: location = 000339B8
location of pointer pd: 0028F7FC
size of pt = 4: size of *pt = 4
size of pd = 4: size of *pd = 8

int * ps = new int;   // allocate memory with new
. . .                 // use the memory
delete ps;            // free memory with delete when done

int * ps = new int;   // ok
delete ps;            // ok
delete ps;            // not ok now
int jugs = 5;         // ok
int * pi = &jugs;     // ok
delete pi;            // not allowed, memory not allocated by new

int * ps = new int; // allocate memory
int * pq = ps;      // set second pointer to same block
delete pq;          // delete with second pointer