SA17225160_李伯威(libowei)_高级软工第五次实验报告

来源：互联网发布：培训班知乎编辑：程序博客网时间：2024/05/15 02:23

一、实验要求

1）给lab5-1.tar.gz的代码找quit函数无法执行的bug

2）利用callback函数参数使Linktable的查询接口更加通用

3）注意接口的信息隐藏

二、实验步骤

1、给lab5-1.tar.gz的代码找quit函数无法执行的bug

1）解压se_files下面的文件lab5-1.tar.gz，进入lab5.1，编译并执行menu程序，发现执行quit命令无法退出程序

2）仔细检查代码,发现linktable.c中的SearchLinkTableNode函数存在问题.while循环条件while(pNode != pLinkTable -> pTail)使得函数在找到链表最后一个节点时即退出循环,因此无法访问最后一个节点.将while(pNode != pLinkTable -> pTail)改为while(pNode != NULL)即可

修改后运行的结果:

2、使用callback函数

1).clone并且新建文件夹子ab5

2).编辑linktable.c

具体代码如下:

#include<stdio.h>#include<stdlib.h>#include"linktable.h"struct LinkTable{    tLinkTableNode *pHead;    tLinkTableNode *pTail;    intSumOfNode;    pthread_mutex_t mutex;};/* * 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;tLinkTableNode * SearchLinkTableNode(tLinkTable *pLinkTable, int Conditon(tLinkTableNode * pNode, void* agrs), void* agrs){    if(pLinkTable == NULL || Conditon == NULL)    {        return NULL;    }    tLinkTableNode * pNode = pLinkTable->pHead;//  while(pNode != pLinkTable->pTail)    while(pNode)    {            if(Conditon(pNode, agrs) == 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)编辑linktable.h

具体代码如下:

#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 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, void* agrs); */tLinkTableNode * SearchLinkTableNode(tLinkTable *pLinkTable, int Conditon(tLinkTableNode * pNode, void* agrs), void* agrs);/* * get LinkTableHead */tLinkTableNode * GetLinkTableHead(tLinkTable *pLinkTable);/* * get next LinkTableNode */tLinkTableNode * GetNextLinkTableNode(tLinkTable *pLinkTable,tLinkTableNode * pNode);#endif /* _LINK_TABLE_H_ */

4)编辑menu.c代码

menu.c的具体代码如下:

#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/* data struct and its operations */typedef struct DataNode{    tLinkTableNode * pNext;    char*   cmd;    char*   desc;    int     (*handler)();} tDataNode;int SearchCondition(tLinkTableNode * pLinkTableNode, void* args){    tDataNode * pNode = (tDataNode *)pLinkTableNode;    char* cmd = (char*)args;    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)    {        char cmd[CMD_MAX_LEN];        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);}

5)编译并且运行:

3.上传github

三、实验总结

回调函数是把函数的指针作为参数传递给另一个函数，回调函数不是由该函数的实现方直接调用，而是在特定的事件或条件发生时由另外的一方调用的，用于对该事件或条件进行响应。回调函数可以允许用户把需要调用的函数的指针作为参数传递给一个函数，以便该函数在处理相似事件的时候可以灵活的使用不同的方法。

我的github:https://github.com/lili0001002/cs122/tree/master

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