c/c++ 杂项知识点

#define   M   10   
#define   N   10   
 
  void   *p;   
  int   **a;   
  p=malloc(sizeof(int)*M*N);   
  a=(int **)p;

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