c 指针兼容性问题

指针兼容性问题:   

  1. const指针不能赋值给非const指针.   
  2. 非const指针可以赋值给const 指针,但前提是只是一层间接运算   
 1   Example:
 2   int *pt1;
 3       const *pt2;
 4       const **pt3;
 5   
 6       pt2=pt1;//OK
 7       pt1=pt2;//NO
 8       pt3=&pt2;//OK
 9       pt3=&pt1;//NO double indirection
10   Problem:
11   pt1=pt2;//NO
12   pt3=&pt2;//OK
13   pt3=&pt1;//NO double indirection
14   
15   Explain:
16   const n=5;
17   Int *p1;
18   Const int **p2;
19   //consumption  p2=&p1; is right
20   p2=&p1;
21   *p2=&n;//OK ,but this mean p1=&n;
22   *p1=10;//OK because p1 is not const ,but that will be contradicted with consumption

 

指针兼容性问题:   const指针不能赋值给非const指针.   非const指针可以赋值给const 指针,但前提是只是一层间接运算   Example:   int *pt1;       const *pt2;       const **pt3;          pt2=pt1;//OK       pt1=pt2;//NO       pt3=&pt2;//OK       pt3=&pt1;//NO double indirection   Problem:   pt1=pt2;//NO   pt3=&pt2;//OK   pt3=&pt1;//NO double indirection      Explain:   const n=5;   Int *p1;   Const int **p2;   //consumption  p2=&p1; is right   p2=&p1;   *p2=&n;//OK ,but this mean p1=&n;   *p1=10;//OK because p1 is not const ,but that will be contradicted with consumption

posted @ 2014-11-30 19:28  陈贞  阅读(69)  评论(0编辑  收藏  举报