c++ 的用 new 和delete 进行二维数组动态内存的创建和删除

 1.数组指针 
A (*ga)[n] = new A[m][n];      
     ... 
    delete []ga;
2.二级指针
 A** ga = new A*[m];
  for(int i = 0; i < m; i++) 
          ga[i] = new A[n]; 
  ... 
   for(int i = 0; i < m; i++)  
           delete []ga[i];
      delete []ga;
3.//用一维数组来模拟
 A* ga = new A[m*n]; 
   ... 
   delete []ga;

对应的用malloc 和free 函数进行操作的方法是：
1.
int (*p)[4] = (int *[])malloc(sizeof(int) *n * m);
free(p);
2. 
int **p;
for(int i = 0; i < n; i ++)
{
    p[i] = (int *)malloc(sizeof(int) * m);
}
for(int i = 0; i < n; i ++)
   free(p[i]);
free(p);
 
3.
int *p  = (int *) malloc(sizeof(int) * n *m);
free(p);