实验3-内部模块化

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

一．     实验过程

Clone github库github.com/wangyufan/SE.git到实验环境

1.进入实验目录并创建实验一文件夹lab3

2.编写.c文件.h文件，实验代码如下：

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

tDataNode* FindCmd(tDataNode* head,char* cmd);

int ShowAllCmd(tDataNode* head);

#include
#include
#include "linklist.h"

tDataNode* FindCmd(tDataNode* head,char* cmd) 
{
	if(head == NULL || cmd == NULL)
	{
		return NULL;
	}
	tDataNode* p = head;
	while(p != NULL)
	{
		if(strcmp(p->cmd,cmd) == 0)
		{
			return p;
		}
		p = p->next;
	}
	return NULL;
}

int ShowAllCmd(tDataNode* head)
{
 	printf("Menu List:\n");
 	tDataNode* p = head;
 	while(p != NULL)
 	{
 		printf("%s-%s\n",p->cmd,p->desc);
 		p = p->next;
	}
	return 0;
 }

#include 
#include 
#include 
#include "linklist.h"

void help();
void upper();
void version();
void lower();
void add();
void sub();
void multi();
void quit();

#define CMD_MAX_LENGTH 128

static tDataNode head[] = 
{
    {"help", "cmd tips.", help, &head[1]},
    {"version","show version of this menu.", version, &head[2]},
    {"quit", "exit cmd.", quit, &head[3]},
    {"upper", "change the case into uppercase Letters.", upper, &head[4]},
    {"lower", "change the case into lowercase Letters.", lower, &head[5]},
    {"sub", "subtraction of two numbers.", sub, &head[6]},
    {"add", "addition of two numbers.", add, &head[7]},
    {"multi", "multiplication of two numbers.", multi, NULL}
};

int main()
{
    char cmd[CMD_MAX_LENGTH];
    while(1)
    {
        printf("menu cmd-> ");
        scanf("%s", cmd);
        tDataNode* p = FindCmd(head, cmd);      
        if(p == NULL)
        {
            printf("error: Wrong command!\n");
        }
        else
        {
            p->handler();
        }
    }
    return 0;
}

void help()
{
    printf("+--------+---------------------------------+\n");
    printf("+ help   + cmd tips                        +\n");
    printf("+ quit   + exit cmd                        +\n");
    printf("+ version+ show version                        +\n");
    printf("+ upper  + change the case into uppercase Letters +\n");
    printf("+ lower  + change the case into lowercase Letters +\n");
    printf("+ sub    + subtraction of two numbers           +\n");
    printf("+ add    + addition of two numbers         +\n");
    printf("+ multi  + multiplication of two numbers   +\n");    
    printf("+--------+---------------------------------+\n");
}

void quit()
{
    exit(0);
}

void upper()
{
    int i;
    char arr[100];
    printf("please input contents:");
    scanf("%s", arr);
    for(i=0; arr[i]!='\0'; i++)
    {
        if(arr[i]>='A'&&arr[i]<='Z')
            arr[i]+=32;
    }
    printf("%s\n", arr);
}

void lower()
{
    int i;
    char arr[100];
    printf("please input contents:");
    scanf("%s", arr);
    for(i=0; arr[i]!='\0'; i++)
    {
        if(arr[i]>='a'&&arr[i]<='z')
            arr[i]-=32;
    }
    printf("%s\n", arr);
}

void version()
{
    printf("the version is 1.0.0\n");
}


void add()
{
    double num1,num2,count;
    printf("+-------*--------*--------*--------*-------+\n");
    printf("please input two numbers:");
    scanf("%lf %lf",&num1, &num2);
    char a;
    count = num1 + num2;
    a = '+';
    printf("%lf  %c %lf = %lf \n",num1, a, num2, count);
}

void sub()
{
    double num1,num2,count;
    printf("+-------*--------*--------*--------*-------+\n");
    printf("please input two numbers:");
    scanf("%lf %lf",&num1, &num2);
    char a;
    count = num1 - num2;
    a = '-';
    printf("%lf  %c %lf = %lf \n",num1, a, num2, count);
}

void multi()
{
    double num1,num2,count;
    printf("+-------*--------*--------*--------*-------+\n");
    printf("please input two numbers:");
    scanf("%lf %lf",&num1, &num2);
    char a;
    count = num1 * num2;
    a = '*';
    printf("%lf  %c %lf = %lf \n",num1, a, num2, count);
}

3实验结果

实现的命令8个:

help帮助

version版本号 

quit退出

upper将字符串中大写字母变小写

lower将字符串中小写字母变大写

add

sub

mult 分别计算两个数的加减乘

4.提交代码到版本库

二. 实验总结

1掌握模块化方法：

数据结构极其操作FindCmd和ShowAllCmd放在linklist.h；

FindCmd和ShowAllCmd的具体实现放在linklist.c；

菜单业务逻辑层放在menu.c；

这样数据存储和功能业务分离，有利于分开维护，实现模块化。

2学习了对于扩展开放，对于修改封闭的开-闭原则

3解决了了实验过程中的bug:

gcc编译出错：initializer element is not constant,

原因： 全局变量的值不能在编译时确定，要在执行时确定