c，const和指针，位置对照表

    int a =1;
    
    const int *p = 0;
     p=&a;
    //*p = 1 ;

    int const *pp = 0;
    pp= &a;
    //*pp = 1;

    int* const pv = 0;
    //pv=&a;
    *pv = 1;

    const int const *pavp = 0;
    //pavp = &a;
    //*pavp = 1;
 
    const int *const pbvp = 0;
    //pbvp = &a;
    //*pbvp = 1;

    int const* const pcvp =0 ;
    //pcvp = &a;
    //*pcvp = 1;

    int a =1;
    typedef int* int_ptr;

    const int_ptr p=0;
    //p=&a;
    *p = 1;

    int_ptr const pa=0;
    //pa=&a;
    *p = 1;