动态申请二维数组并释放

#include <iostream>
using namespace std;

//定义类型A
class A
{
public:
friend class B;  //类型B为友元类
private:
int **p;                //指向二级数组
int m_n1;                //行数
int m_n2;                //列数

public:
A(int n1, int n2);        //生成二维数据
~A();
void InitA();            //初始化对象A
};

A::A(int n1, int n2)
{
m_n1 = n1;                //记录二维数组行数
m_n2 = n2;                //记录二维数组列数
p = new int* [n1];

for(int i=0; i<n1; ++i)
{
p[i] = new int [n2];
}
}

A::~A()
{
for (int i=0; i<m_n1; ++i)
{
delete[] p[i];
}
delete[] p;
}

void A::InitA()
{
for (int i=0; i<m_n1; ++i)
{
for (int j=0; j<m_n2; ++j)
{
p[i][j] = i*m_n2 + j;
}
}
}

//定义类型B
class B
{
public:
void Print(const A& a1);//打印二维数组内的元素
};

void B::Print(const A& a1)
{
for (int i=0; i<a1.m_n1; ++i)
{
for (int j=0; j<a1.m_n2; ++j)
{
cout << a1.p[i][j] << ' ';
}
cout << endl;
}
}

int main()
{
A a(2, 4);
a.InitA();
B b;
b.Print(a);
}

//-----------------------------------------------------------------
//-----------------------------------------------------------------
//-----------------------------------------------------------------
//-----------------------------------------------------------------

//C++里 数组new 和delete问题
//对于数组new的不同方式 和不同的释放方法
//----------------------------------------------------------------
// 创建字符指针数组
char **parr = new char*[100];
for (int i=0;i<100;++i)
{
parr[i]=new char [50];
}
// 释放各个字符数组
for (int i =0; i < 100; i++)
delete [] parr[i];
//释放字符指针数组
delete [] parr;

//---------------------------------------------------------------
// 创建数组
int *parr = new int[100];
// 释放数组
delete [] parr;