1 指针

&i i的地址，*pp指向的内容

指针的指针

int main()
{
    int i = 30;
    cout << "&i = " << &i << endl;
    cout << "i = " << i << endl;
    int *pi = &i;
    cout << "*pi = " << *pi << endl;
    cout << "&pi = " << &pi << endl;
    int **ppi = &pi;
    cout << "**ppi = " << **ppi << endl;
    system("pause");
    return 0;
}
&i = 0x61ff08
i = 30
*pi = 30
&pi = 0x61ff08
**ppi = 30

间接数据访问

改变一级指针指向

int main()
{
    int i = 30;
    int *pi = &i;
    cout << "一级指针*pi= " << *pi << endl; // 一级指针*pi= 30
    cout << "一级指针pi= " << pi << endl; // 一级指针pi= 0x61ff08

    int **ppi = &pi;
    cout << "二级指针**pi= " << **ppi << endl; // 二级指针**pi= 30
    cout << "二级指针ppi= " << ppi << endl; // 二级指针ppi= 0x61ff04

    *pi = 20;
    cout << "改变一级指针值 *pi = " << *pi << endl; // 改变一级指针值 *pi = 20
    cout << " pi = " << pi << endl; //  pi = 0x61ff08

    cout << "二级指针**ppi= " << **ppi << endl; // 二级指针**ppi= 20
    cout << "二级指针ppi= " << ppi << endl; // 二级指针ppi= 0x61ff04

    int b = 10;
    *ppi = &b;
    cout << "改变一级指针指向 *pi = " << *pi << endl; // 改变一级指针指向 *pi = 10
    cout << " pi = " << pi << endl; // pi = 0x61ff00

    cout << "二级指针**ppi= " << **ppi << endl; // 二级指针**ppi= 10
    cout << "二级指针ppi= " << ppi << endl; //二级指针ppi= 0x61ff04
    cout << "&b = " << &b << endl; // &b = 0x61ff00


    cout << *ppi << " " << pi << endl;  // 0x61ff00 0x61ff00

    return 0;

可以通过n级指针修改n-1级指针的指向。

指针和数组

*P++ 修改指针 ； *(p+i)不修改指针

int main()
{
    int var[MAX] = {10, 100, 200};
    int *ptr;

    // 指针中的数组地址
    ptr = var;
    for (int i = 0; i < MAX; ++i)
    {
        cout << "addreass of var[" << i << "] = ";
        cout << ptr << endl;
        cout << "value of var[" << i << "] = ";
        cout << *ptr++ << endl;    // 修改指针
        /* cout << *(ptr+i) << endl;    不修改指针 */
        cout << "var[" << i << "] = " << var[i] << endl;

    }
    return 0;
}

addreass of var[0] = 0x61fefc
value of var[0] = 10
var[0] = 10
addreass of var[1] = 0x61ff00
value of var[1] = 100
var[1] = 100
addreass of var[2] = 0x61ff04
value of var[2] = 200
var[2] = 200

指针数组

int var[3] = {10,20,30};
int *p[3];
char *names[3] = {"10","20","30"}

函数传入指针 type xx(type xx/ type 数组名)

从函数返回指针 type * xx(){}

#include <iostream>
#include <ctime>
using namespace std;

const int MAX = 3;
int* getRandom()
{
    static int r[3];
    srand((unsigned)time(NULL));
    for (int i = 0; i < 3;i++)
    {
        r[i] = rand();
        cout << r[i] << endl;
    }
    return r;
}
int main()
{
    int *p;
    p = getRandom();
    for (int i = 0; i < 3;i++)
    {
        cout << "*(p + " << i << ")" << *(p + i) << endl;
    }
    return 0;
}