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

【孙剑峰 SA16225264 + 《软件工程（C编码实践篇）》MOOC课程作业http://mooc.study.163.com/course/USTC-1000002006】

代码地址： http://git.shiyanlou.com/csxiaoyao/shiyanlou_cs122/src/master

1. 实验要求

1. 用可重用的链表模块来实现命令行菜单小程序，执行某个命令时调用一个特定的函数作为执行动作
2. 链表模块的接口设计要足够通用，命令行菜单小程序的功能保持不变
3. 可以将通用的Linktable模块集成到menu程序中
4. 接口规范

2. 实验思路

创建目录 lab4，定义 menu.c, linktable.c, linktable.h, testlinktable.c 四个文件，将通用的 Linktable 模块集成到 menu 程序中

3. 实验过程

在lab4中创建 linktable.h、linktable.c、menu.c 文件并编辑，实验代码如下：

3.1 linktable.h

#ifndef _LINK_TABLE_H_
#define _LINK_TABLE_H_
#define SUCCESS 0
#define FAILURE (-1)

typedef struct LinkTableNode
{
     struct LinkTableNode * pNext;
} tLinkTableNode;
typedef struct LinkTable
{
    tLinkTableNode *pHead;
    tLinkTableNode *pTail;
    int SumOfNode;
} 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);
// Get LinktableHead
tLinkTableNode *GetLinkTableHead(tLinkTable *pLinkTable);
// Get next LinktableNode
tLinkTableNode *GetNextLinkTableNode(tLinkTable *pLinkTable,tLinkTableNode *pNode);

#endif // _LINK_TABLE_H_

3.2 linktable.c

#include <stdio.h>
#include <stdlib.h>
#include "linktable.h"

tLinkTable *CreateLinkTable()
{
    tLinkTable *pLinkTable = (tLinkTable*)malloc(sizeof(tLinkTable));
    if(pLinkTable == NULL)
    {
        return NULL;
    }
    pLinkTable->pHead = NULL;
    pLinkTable->pTail = NULL;
    pLinkTable->SumOfNode = 0;
    return pLinkTable;
}

int DeleteLinkTable(tLinkTable *pLinkTable)
{
    if(pLinkTable == NULL)
    {
        return FAILURE;
    }
    while(pLinkTable->pHead != NULL)
    {
        tLinkTableNode *tmp = pLinkTable->pHead;
        pLinkTable->pHead = pLinkTable->pHead->pNext;
        free(tmp);
    }
    pLinkTable->pHead = NULL;
    pLinkTable->pTail = NULL;
    pLinkTable->SumOfNode = -1;
    free(pLinkTable);
    return SUCCESS;
}

int AddLinkTableNode(tLinkTable *pLinkTable,tLinkTableNode *pNode)
{
    if(pLinkTable == NULL || pNode == NULL)
    {
        return FAILURE;
    }
    if(pLinkTable->pHead == NULL)
    {
        pLinkTable->pHead = pNode;
        pLinkTable->pTail = pNode;
        pLinkTable->SumOfNode = 1;
    }
    else
    {
        pLinkTable->pTail->pNext = pNode;
        pLinkTable->pTail = pNode;
        pLinkTable->SumOfNode ++;
    }
    return SUCCESS;
}

int DelLinkTableNode(tLinkTable *pLinkTable,tLinkTableNode *pNode)
{
    if(pLinkTable == NULL ||pNode == NULL)
    {
        return FAILURE;
    }
    if(pLinkTable->pHead == pNode)
    {
        tLinkTableNode *tmp = pLinkTable->pHead;
        pLinkTable->pHead = pLinkTable->pHead->pNext;
        free(tmp);
        pLinkTable->SumOfNode--;
    }
    if(pLinkTable->SumOfNode == 0)
    {
        pLinkTable->pTail = NULL;
        return FAILURE;
    }
    tLinkTableNode *tmp = pLinkTable->pHead;
    while(tmp != NULL)
    {
        if(tmp->pNext == pNode)
        {
            tmp->pNext = pNode ->pNext;
            pLinkTable->SumOfNode --;
            if(pLinkTable->SumOfNode == 0)
            {
                pLinkTable->pTail = NULL;
            }
            return SUCCESS;
        }
        tmp = tmp->pNext;
    }
    return FAILURE;
}

tLinkTableNode * GetLinkTableHead(tLinkTable *pLinkTable)
{
    if(pLinkTable == NULL||pLinkTable->pHead == NULL)
    {
        return NULL;
    }
    return pLinkTable->pHead;
}

tLinkTableNode *GetNextLinkTableNode(tLinkTable *pLinkTable,tLinkTableNode *pNode)
{
    if(pLinkTable == NULL||pNode == NULL)
    {
    return NULL;
    }
    tLinkTableNode *tmp = pLinkTable->pHead;
    while(tmp != NULL)
    {
        if(tmp == pNode)
        {
            return tmp->pNext;
        }
        tmp = tmp->pNext;
    }
    return NULL;
}

3.3 menu.c

#include <stdio.h>
#include <stdlib.h>
#include "linktable.h"

#define CMD_MAX_LEN 128
#define CMD_DESC_LEN 1024
#define CMD_NUM 10

typedef struct DataNode
{
    tLinkTableNode *pNext;
    char* cmd;
    char* desc;
    int (*handler)();
}tDataNode;

tDataNode* FindCmd(tLinkTable *head,char *cmd)
{
    tDataNode *pNode = (tDataNode*)GetLinkTableHead(head);
    while(pNode != NULL)
    {
        if(strcmp(pNode->cmd,cmd) == 0)
        {
            return pNode;
        }
        pNode = (tDataNode*)GetNextLinkTableNode(head,(tLinkTableNode*)pNode);
    }
    return NULL;
}

int Help();
int Quit();
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;
}

tLinkTable *head = NULL;
int main()
{
    InitMenuData(&head);
    char cmd[CMD_MAX_LEN];
    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();
        }
    }
    return 0;
}

int Help()
{
    ShowAllCmd(head);
    return 0;
}
int Quit()
{
    exit(0);
    return 0;
}

4. 运行结果

5. 实验总结

这次实验复习了对链表的操作，对可重用的理解得到进一步提升