“软件工程(C编码实践篇)”实验报告【实验五:用callback增强链表模块来实现命令行菜单小程序V2.8】
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2022-07-16 17:30:10
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实验资料
- 网易云课程地址:实验四:用可重用的链表模块来实现命令行菜单小程序V2.5
- 网易云课堂昵称:Natsukashiii
- 学号:SA17225129
- 我的github地址
实验要求
本实验在提供的代码基础上进行
- 给lab5-1.tar.gz找bug,quit命令无法运行的bug
- 利用callback函数参数使Linktable的查询接口更加通用
- 注意接口的信息隐藏
实验内容
- 用gcc命令编译作业中给出的代码,发现显示一个warning,但不影响运行;
- 运行menu.c程序,并尝试后发现,help、quit、version三个命令中,help和version命令能正常运行,但不能使用quit命令,会显示“This is a wrong cmd!”;
- 观察“quit”命令的程序代码,发现linktable.c中函数SearchLinkTableNode的while循环条件有问题,改为pNode!=NULL后程序即可正常运行;
- 使用callback增强链表模块;
实验思路
- 本次实验室根据老师提供的代码,找出bug,并进行修改,在运行程序观察错误后,找到出现错误的quit命令,在源代码中发现是while循环条件出现问题,修改后便能正确运行程序代码;
- 在代码正确的基础上对实验代码进行优化,通过callback函数的方式实现命令的查询,有利于程序的结构化设计。
实验过程
1.用gcc命令编译作业中给出的代码,发现显示一个warning,但不影响运行;
2.运行menu.c程序,并尝试后发现,help、quit、version三个命令中,help和version命令能正常运行,但不能使用quit命令,会显示“This is a wrong cmd!”;
3.观察“quit”命令的程序代码,发现linktable.c中函数SearchLinkTableNode的while循环条件有问题,源代码判断的是结点是尾结点的话就退出,则在链表的最后一个结点时,判断其为尾结点,直接返回NULL,所以quit最后一个命令无法执行,应当改成pNode !=NULL则运行正确。
/*
* 原代码
* Search a LinkTableNode from LinkTable
* int Conditon(tLinkTableNode * pNode);
*/
tLinkTableNode * SearchLinkTableNode(tLinkTable *pLinkTable, int Conditon(tLinkTableNode * pNode))
{
if(pLinkTable == NULL || Conditon == NULL)
{
return NULL;
}
tLinkTableNode * pNode = pLinkTable->pHead;
while(pNode != pLinkTable->pTail) //此处while循环条件有误
{
if(Conditon(pNode) == SUCCESS)
{
return pNode;
}
pNode = pNode->pNext;
}
return NULL;
}
正确代码为:
/*
* 修改后的代码
* Search a LinkTableNode from LinkTable
* int Conditon(tLinkTableNode * pNode);
*/
tLinkTableNode * SearchLinkTableNode(tLinkTable *pLinkTable, int Conditon(tLinkTableNode * pNode))
{
if(pLinkTable == NULL || Conditon == NULL)
{
return NULL;
}
tLinkTableNode * pNode = pLinkTable->pHead;
while(pNode !=NULL) //将循环条件修改为判断结点是否为空
{
if(Conditon(pNode) == SUCCESS)
{
return pNode;
}
pNode = pNode->pNext;
}
return NULL;
}
4.此时再次编译运行代码,运行成功;
5.使用callback增强链表模块,先修改linktable.h代码;
6.修改linktable.c代码;
7.修改menu.c代码;
8.最后进行git add,git commit,git push命令提交修改至我的github仓库。
实验代码
1.linkable.h
/********************************************************************/
/* Copyright (C) SSE-USTC, 2012-2013 */
/* */
/* FILE NAME : linktabe.h */
/* PRINCIPAL AUTHOR : Mengning */
/* SUBSYSTEM NAME : LinkTable */
/* MODULE NAME : LinkTable */
/* LANGUAGE : C */
/* TARGET ENVIRONMENT : ANY */
/* DATE OF FIRST RELEASE : 2012/12/30 */
/* DESCRIPTION : interface of Link Table */
/********************************************************************/
/*
* Revision log:
*
* Created by Mengning,2012/12/30
*
*/
#ifndef _LINK_TABLE_H_
#define _LINK_TABLE_H_
#include <pthread.h>
#define SUCCESS 0
#define FAILURE (-1)
/*
* LinkTable Node Type
*/
typedef struct LinkTableNode
{
struct LinkTableNode * pNext;
}tLinkTableNode;
/*
* LinkTable Type
*/
typedef struct LinkTable
{
tLinkTableNode *pHead;
tLinkTableNode *pTail;
int SumOfNode;
pthread_mutex_t mutex;
}tLinkTable;
/*
* Create a LinkTable
*/
tLinkTable * CreateLinkTable();
/*
* Delete a LinkTable
*/
int DeleteLinkTable(tLinkTable *pLinkTable);
/*
* Add a LinkTableNode to LinkTable
*/
int AddLinkTableNode(tLinkTable *pLinkTable,tLinkTableNode * pNode);
/*
* Delete a LinkTableNode from LinkTable
*/
int DelLinkTableNode(tLinkTable *pLinkTable,tLinkTableNode * pNode);
/*
* Search a LinkTableNode from LinkTable
* int Conditon(tLinkTableNode * pNode);
*/
tLinkTableNode * SearchLinkTableNode(tLinkTable *pLinkTable, int Conditon(tLinkTableNode * pNode,void args),void *args);
/*
* get LinkTableHead
*/
tLinkTableNode * GetLinkTableHead(tLinkTable *pLinkTable);
/*
* get next LinkTableNode
*/
tLinkTableNode * GetNextLinkTableNode(tLinkTable *pLinkTable,tLinkTableNode * pNode);
#endif /* _LINK_TABLE_H_ */
2.linkable.c
/********************************************************************/
/* Copyright (C) SSE-USTC, 2012-2013 */
/* */
/* FILE NAME : linktabe.c */
/* PRINCIPAL AUTHOR : Mengning */
/* SUBSYSTEM NAME : LinkTable */
/* MODULE NAME : LinkTable */
/* LANGUAGE : C */
/* TARGET ENVIRONMENT : ANY */
/* DATE OF FIRST RELEASE : 2012/12/30 */
/* DESCRIPTION : interface of Link Table */
/********************************************************************/
/*
* Revision log:
*
* Created by Mengning,2012/12/30
* Provide right Callback interface by Mengning,2012/09/17
*
*/
#include<stdio.h>
#include<stdlib.h>
#include"linktable.h"
/*
* Create a LinkTable
*/
tLinkTable * CreateLinkTable()
{
tLinkTable * pLinkTable = (tLinkTable *)malloc(sizeof(tLinkTable));
if(pLinkTable == NULL)
{
return NULL;
}
pLinkTable->pHead = NULL;
pLinkTable->pTail = NULL;
pLinkTable->SumOfNode = 0;
pthread_mutex_init(&(pLinkTable->mutex), NULL);
return pLinkTable;
}
/*
* Delete a LinkTable
*/
int DeleteLinkTable(tLinkTable *pLinkTable)
{
if(pLinkTable == NULL)
{
return FAILURE;
}
while(pLinkTable->pHead != NULL)
{
tLinkTableNode * p = pLinkTable->pHead;
pthread_mutex_lock(&(pLinkTable->mutex));
pLinkTable->pHead = pLinkTable->pHead->pNext;
pLinkTable->SumOfNode -= 1 ;
pthread_mutex_unlock(&(pLinkTable->mutex));
free(p);
}
pLinkTable->pHead = NULL;
pLinkTable->pTail = NULL;
pLinkTable->SumOfNode = 0;
pthread_mutex_destroy(&(pLinkTable->mutex));
free(pLinkTable);
return SUCCESS;
}
/*
* Add a LinkTableNode to LinkTable
*/
int AddLinkTableNode(tLinkTable *pLinkTable,tLinkTableNode * pNode)
{
if(pLinkTable == NULL || pNode == NULL)
{
return FAILURE;
}
pNode->pNext = NULL;
pthread_mutex_lock(&(pLinkTable->mutex));
if(pLinkTable->pHead == NULL)
{
pLinkTable->pHead = pNode;
}
if(pLinkTable->pTail == NULL)
{
pLinkTable->pTail = pNode;
}
else
{
pLinkTable->pTail->pNext = pNode;
pLinkTable->pTail = pNode;
}
pLinkTable->SumOfNode += 1 ;
pthread_mutex_unlock(&(pLinkTable->mutex));
return SUCCESS;
}
/*
* Delete a LinkTableNode from LinkTable
*/
int DelLinkTableNode(tLinkTable *pLinkTable,tLinkTableNode * pNode)
{
if(pLinkTable == NULL || pNode == NULL)
{
return FAILURE;
}
pthread_mutex_lock(&(pLinkTable->mutex));
if(pLinkTable->pHead == pNode)
{
pLinkTable->pHead = pLinkTable->pHead->pNext;
pLinkTable->SumOfNode -= 1 ;
if(pLinkTable->SumOfNode == 0)
{
pLinkTable->pTail = NULL;
}
pthread_mutex_unlock(&(pLinkTable->mutex));
return SUCCESS;
}
tLinkTableNode * pTempNode = pLinkTable->pHead;
while(pTempNode != NULL)
{
if(pTempNode->pNext == pNode)
{
pTempNode->pNext = pTempNode->pNext->pNext;
pLinkTable->SumOfNode -= 1 ;
if(pLinkTable->SumOfNode == 0)
{
pLinkTable->pTail = NULL;
}
pthread_mutex_unlock(&(pLinkTable->mutex));
return SUCCESS;
}
pTempNode = pTempNode->pNext;
}
pthread_mutex_unlock(&(pLinkTable->mutex));
return FAILURE;
}
/*
* Search a LinkTableNode from LinkTable
* int Conditon(tLinkTableNode * pNode);
*/
tLinkTableNode * SearchLinkTableNode(tLinkTable *pLinkTable, int Conditon(tLinkTableNode * pNode), void *args)
{
if(pLinkTable == NULL || Conditon == NULL)
{
return NULL;
}
tLinkTableNode * pNode = pLinkTable->pHead;
while(pNode !=NULL)
{
if(Conditon(pNode) == SUCCESS)
{
return pNode;
}
pNode = pNode->pNext;
}
return NULL;
}
/*
* get LinkTableHead
*/
tLinkTableNode * GetLinkTableHead(tLinkTable *pLinkTable)
{
if(pLinkTable == NULL)
{
return NULL;
}
return pLinkTable->pHead;
}
/*
* get next LinkTableNode
*/
tLinkTableNode * GetNextLinkTableNode(tLinkTable *pLinkTable,tLinkTableNode * pNode)
{
if(pLinkTable == NULL || pNode == NULL)
{
return NULL;
}
tLinkTableNode * pTempNode = pLinkTable->pHead;
while(pTempNode != NULL)
{
if(pTempNode == pNode)
{
return pTempNode->pNext;
}
pTempNode = pTempNode->pNext;
}
return NULL;
}
3.menu.c
/**************************************************************************************************/
/* Copyright (C) mc2lab.com, aaa@qq.com, 2014-2015 */
/* */
/* FILE NAME : menu.c */
/* PRINCIPAL AUTHOR : Mengning */
/* SUBSYSTEM NAME : menu */
/* MODULE NAME : menu */
/* LANGUAGE : C */
/* TARGET ENVIRONMENT : ANY */
/* DATE OF FIRST RELEASE : 2014/08/31 */
/* DESCRIPTION : This is a menu program */
/**************************************************************************************************/
/*
* Revision log:
*
* Created by Mengning, 2014/08/31
*
*/
#include <stdio.h>
#include <stdlib.h>
#include "linktable.h"
int Help();
int Quit();
#define CMD_MAX_LEN 128
#define DESC_LEN 1024
#define CMD_NUM 10
char cmd[CMD_MAX_LEN];
/* data struct and its operations */
typedef struct DataNode
{
tLinkTableNode * pNext;
char* cmd;
char* desc;
int (*handler)();
} tDataNode;
int SearchCondition(tLinkTableNode * pLinkTableNode, void *args)
{
char *cmd = (char*)args;
tDataNode * pNode = (tDataNode *)pLinkTableNode;
if(strcmp(pNode->cmd, cmd) == 0)
{
return SUCCESS;
}
return FAILURE;
}
/* find a cmd in the linklist and return the datanode pointer */
tDataNode* FindCmd(tLinkTable * head, char * cmd)
{
return (tDataNode*)SearchLinkTableNode(head,SearchCondition,(void*)cmd);
}
/* show all cmd in listlist */
int ShowAllCmd(tLinkTable * head)
{
tDataNode * pNode = (tDataNode*)GetLinkTableHead(head);
while(pNode != NULL)
{
printf("%s - %s\n", pNode->cmd, pNode->desc);
pNode = (tDataNode*)GetNextLinkTableNode(head,(tLinkTableNode *)pNode);
}
return 0;
}
int InitMenuData(tLinkTable ** ppLinktable)
{
*ppLinktable = CreateLinkTable();
tDataNode* pNode = (tDataNode*)malloc(sizeof(tDataNode));
pNode->cmd = "help";
pNode->desc = "Menu List:";
pNode->handler = Help;
AddLinkTableNode(*ppLinktable,(tLinkTableNode *)pNode);
pNode = (tDataNode*)malloc(sizeof(tDataNode));
pNode->cmd = "version";
pNode->desc = "Menu Program V1.0";
pNode->handler = NULL;
AddLinkTableNode(*ppLinktable,(tLinkTableNode *)pNode);
pNode = (tDataNode*)malloc(sizeof(tDataNode));
pNode->cmd = "quit";
pNode->desc = "Quit from Menu Program V1.0";
pNode->handler = Quit;
AddLinkTableNode(*ppLinktable,(tLinkTableNode *)pNode);
return 0;
}
/* menu program */
tLinkTable * head = NULL;
int main()
{
InitMenuData(&head);
/* cmd line begins */
while(1)
{
printf("Input a cmd number > ");
scanf("%s", cmd);
tDataNode *p = FindCmd(head, cmd);
if( p == NULL)
{
printf("This is a wrong cmd!\n ");
continue;
}
printf("%s - %s\n", p->cmd, p->desc);
if(p->handler != NULL)
{
p->handler();
}
}
}
int Help()
{
ShowAllCmd(head);
return 0;
}
int Quit()
{
exit(0);
}
实验总结
- 进一步了解了结构体和链表的操作的使用和指针操作也有了更深入的了解;
- 函数交由callback来处理,这样有利于程序的结构化设计。