二维数组与指针

#include<iostream>
using namespace std;

int ia[3][4] =
{
    {0, 1, 2, 3},
    {4, 5, 6, 7},
    {8, 9, 10, 11}
};
int main()
{
    cout << "sizeof(int): " << sizeof(int) << endl;

//      sizeof(int): 4
//   ---------------------ia[3][4]--------------------------
    cout << "ia: " << ia << "\t";
    cout << "sizeof(ia): " << sizeof(ia) << endl;
    cout << "*ia: " << *ia << "\t";
    cout << "sizeof(*ia): " << sizeof(*ia) << endl;
    cout << "&ia: " << &ia << "\t";
    cout << "sizeof(&ia): " << sizeof(&ia) << endl;
    cout << "ia[2]: " << ia[2] << "\t";
    cout << "sizeof(ia[2]): " << sizeof(ia[2]) << endl;
    cout << "*ia[2]: " << *ia[2] << "\t";
    cout << "sizeof(*ia[2]): " << sizeof(*ia[2]) << endl;
    cout << "&ia[2]: " << &ia[2] << "\t";
    cout << "sizeof(&ia[2]): " << sizeof(&ia[2]) << endl;
    cout << endl;

    /*------------------初始化----------------
    sizeof(int): 4
     ia:         0x46e000     sizeof(ia): 48
    *ia:         0x46e000     sizeof(*ia): 16
    &ia:         0x46e000    sizeof(&ia): 4
     ia[2]:     0x46e020    sizeof(ia[2]): 16
    *ia[2]:     8            sizeof(*ia[2]): 4
    &ia[2]:     0x46e020     sizeof(&ia[2]): 4

    */

//   ---------------------(*ip)[4] = ia--------------------------
    cout << endl;
    int (*ip)[4] = ia;     //(数组)变量的名字其实是指针，因此你需在标识符前加上*。
    cout << "ip: " << ip << "\t";
    cout << "sizeof(ip): " << sizeof(ip) << endl;
    cout << "*ip: " << *ip << "\t";
    cout << "sizeof(*ip): " << sizeof(*ip) << endl;
    cout << "&ip: " << &ip << "\t";
    cout << "sizeof(&ip): " << sizeof(&ip) << endl;
    cout << "ip[3]: " << ip[3] << "\t";
    cout << "sizeof(ip[3]): " << sizeof(ip[3]) << endl;
    cout << "*ip[3]: " << *ip[3] << "\t";
    cout << "sizeof(*ip[3]): " << sizeof(*ip[3]) << endl;
    cout << "&ip[3]: " << &ip[3] << "\t";
    cout << "sizeof(&ip[3]): " << sizeof(&ip[3]) << endl;

    cout << endl;

    /*------------------初始化----------------

     ip:        0x46e000   sizeof(ip): 4
    *ip:         0x46e000    sizeof(*ip): 16
    &ip:         0x22fef4    sizeof(&ip): 4
     ip[3]:      0x46e030    sizeof(ip[3]): 16
    *ip[3]:     0           sizeof(*ip[3]): 4
    &ip[3]:     0x46e030    sizeof(&ip[3]): 4

    */

//   ---------------------(*ip1)[4] = ia; *ip2 = *ia;--------------------------
    int (*ip1)[4] = ia;     //(数组)变量的名字其实是指针，因此你需在标识符前加上*。
    //ip1是等效于ia的二维数组。
    int *ip2 = *ia;         //ip2是指向二维数组ia第一内层数组的一维数组(unary array)，
    //即与ia[0][4]={0, 1, 2, 3},相同，ip[4]={0, 1, 2, 3}
    cout << "ip1: " << ip1 << "\t";
    cout << "sizeof(ip1): "  << sizeof(ip1) << endl;
    cout << "ip2: " << ip2 << "\t";

    cout << "sizeof(ip2): "  << sizeof(ip2) << endl;

    cout << endl;
    cout << "*ip1: " << *ip1 << "\t";
    cout << "sizeof(*ip1): "  << sizeof(*ip1) << endl;
    cout << "*ip2: " << *ip2 << "\t";
    cout << "sizeof(*ip2): "  << sizeof(*ip2) << endl;

    cout << endl;
    cout << "*(ip1 + 1): " << *(ip1 + 1) << "\t";
    cout << "ip1[1]: " << ip1[1] << endl;
    cout << "*(ip2 + 1): " << *(ip2 + 1) << "\t";
    cout << "ip2[1]: " << ip2[1] << endl;

    cout << "**(ip1 + 1): " << **(ip1 + 1) << "\t";
    cout << "ip1[1][0]: " << ip1[1][0] << endl;
    // cout << "**(ip2 + 1): " << **(ip2 + 1) << "\t";       //ip2是一维数组
    // cout << "ip2[2][0]: " << ip2[2][0] << endl;            //ip2是一维数组

    cout << "(*(ip1 + 1))[1]: " << (*(ip1 + 1))[1] << "\t";
    cout << "ip1[1][1]: " << ip1[1][1] << endl;
    //cout << "(*(ip2 + 1))[1]: " << (*(ip2 + 1))[1] << "\t";       //ip2是一维数组
    //cout << "ip2[2][1]: " << ip2[2][1] << endl;                    //ip2是一维数组
    cout << endl;

    /* /*------------------初始化----------------

    ip1:        0x46e000   sizeof(ip1): 4
    ip2:        0x46e000   sizeof(ip2): 4

    *ip1:       0x46e000  sizeof(*ip1): 16
    *ip2:       0         sizeof(*ip2): 4

    *(ip1 + 1):     0x46e010    p1[1]: 0x46e010
    *(ip2 + 1):     1           ip2[1]: 1
    **(ip1 + 1):     4           ip1[1][0]: 4
    (*(ip1 + 1))[1]: 5           ip1[1][1]: 5

    */
//   ---------------------ip = &ia[2];--------------------------
    ip = &ia[2];
    cout << "ip: " << ip << "\t";             //输出为：0x22fefc
    cout << "sizeof(ip): " << sizeof(ip) << endl;
    cout << "*ip: " << *ip << "\t";             //输出为：0x22fefc
    cout << "sizeof(*ip): " << sizeof(*ip) << endl;
    cout << endl;
    /*------------------初始化----------------
    
     ip: 0x46e020    sizeof(ip): 4
    *ip: 0x46e020    sizeof(*ip): 16
    */
    //   ---------------------typedef--------------------------
    cout << "typedef : " << endl;
    typedef  int int_array[4];
    int_array *p = ia;
    for(int_array *p = ia; p != ia + 3; ++p)
        for(int *q = *p, i = 1; q != *p + 4; ++q, ++i)
        {
            cout << *q << "\t";
            if(i % 4 == 0)
                cout << endl;
        }
    cout << endl;

    /* /*--------------------初始化----------------
    typedef :
    0       1       2       3
    4       5       6       7
    8       9       10      11
    */
    return 0;
}

/*结果分析：

------------------------ia[3][4]----------------------------

sizeof(int): 4
ia: 0x46e000    sizeof(ia): 48
*ia: 0x46e000   sizeof(*ia): 16
&ia: 0x46e000   sizeof(&ia): 4
ia[2]: 0x46e020 sizeof(ia[2]): 16
*ia[2]: 8       sizeof(*ia[2]): 4
&ia[2]: 0x46e020      sizeof(&ia[2]): 4

-----------------------(*ip)[4] = ia;-----------------------

ip: 0x46e000    sizeof(ip): 4
*ip: 0x46e000   sizeof(*ip): 16
&ip: 0x22fef4   sizeof(&ip): 4
ip[3]: 0x46e030 sizeof(ip[3]): 16
*ip[3]: 0       sizeof(*ip[3]): 4

&ip[3]: 0x46e030       sizeof(&ip[3]): 4

------------------------(*ip1)[4] = ia; -------------------

------------------------*ip2 = *ia-------------------------

ip1: 0x46e000   sizeof(ip1): 4
ip2: 0x46e000   sizeof(ip2): 4

*ip1: 0x46e000  sizeof(*ip1): 16
*ip2: 0 sizeof(*ip2): 4

*(ip1 + 1): 0x46e010    ip1[1]: 0x46e010
*(ip2 + 1): 1   ip2[1]: 1
**(ip1 + 1): 4  p1[1][0]: 4
(*(ip1 + 1))[1]: 5      ip1[1][1]: 5
--------------------------ip = &ia[2];-----------------------------
ip: 0x46e020    sizeof(ip): 4

*ip: 0x46e020   sizeof(*ip): 16

----------------------------typedef--------------------------------

typedef :
0       1       2       3
4       5       6       7
8       9       10      11




Process returned 0 (0x0)   execution time : 3.861 s
Press any key to continue.

*/

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——桑海整理