斯坦福大学：编程方法学 Lesson three

1.common errors(OBOB)

2.comment 注释

/*   */  段注释

//         行注释

3.decomposition    “Top  Down design”

　　　　分解　　　　　　自顶向下设计

4.doublebeeper

 1 import stanford.karel.*;
 2 public class DoubleBeeper extends Karel{
 3     int num=0;
 4     public void run(){
 5         move();
 6         doublebeeper();
 7         moveback();
 8     }
 9     public void moveback(){
10         turnAround();
11         move();
12         turnAround();
13     }
14     public void turnAround(){
15         turnLeft();
16         turnLeft();
17     }
18     public void doublebeeper(){
19         while(beepersPresent()){
20             pickBeeper();
21             num++;
22         }
23         for(int i=0;i<2*num;i++){
24             putBeeper();
25         }
26     }
27 }

5.cleanBeeper

 1 import stanford.karel.*;
 2 public class CleanBeeper extends Karel{
 3     public void run(){
 4             cleanRowBeeper();
 5             while(leftIsClear()){
 6             rightGoTop();
 7             cleanRowBeeper();
 8             if(rightIsClear()){
 9                 leftGoTop();
10                 cleanRowBeeper();
11             }
12             else{
13                 turnAround();
14             }
15         }
16     }
17     public void cleanRowBeeper(){
18         while(frontIsClear()){
19             if(beepersPresent())
20                 pickBeeper();
21             move();
22         }
23         if(beepersPresent())
24             pickBeeper();
25     }
26     public void rightGoTop(){
27         turnLeft();
28         move();
29         turnLeft();
30     }
31     public void leftGoTop(){
32         turnRight();
33         move();
34         turnRight();
35     }
36     public void turnRight(){
37         turnLeft();
38         turnLeft();
39         turnLeft();
40     }
41     public void turnAround(){
42         turnLeft();
43         turnLeft();
44     }
45 }