链表实现通讯录

初学者 第一次写通讯录，写到头皮发麻。

灵活运用指针函数，返回值为指针

注意使用二级指针操作头指针head

注意del函数的判断条件
切记不骄不躁！

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <malloc.h>

#define LEN sizeof(struct information)
//定义结构体
typedef struct information
{
    char name[20];
    char id[20];
    char phone[20];
    char home[20];
    struct information *next;
}INFO;

//主菜单函数
void face()
{
    printf("******address list*****\n");
    printf("1:show  all information\n");
    printf("2:add       information\n");
    printf("3:delete    information\n");
    printf("4:modify    information\n");
    printf("5:search    information\n");
    printf("0:quit\n");
    printf("***********************\n");
}
//显示所有联系人
INFO *print(INFO *head)
{
    INFO *p;
    p = head;
    //system("clear");

    if(head != NULL)
    {
    	 printf("***********************\n");
        printf("members are as follow!\n");
        while(p != NULL)
        {
            printf("name:%s\t",p->name);
            printf("id:%s\t",p->id);
            printf("phone:%s\t",p->phone);
            printf("home:%s\n",p->home);
            p = p->next;
        }
    }

    else
    {
    	 printf("***********************\n");
        printf("address_list is none!\n");
    }
    return head;
}
//增加联系人函数
INFO *add(INFO *head)
{
	INFO *new_node = (INFO*)malloc(LEN);
	
    printf("***********************\n");
    printf("please input name!\n");
    scanf("%s",new_node->name);
    printf("please input id!\n");
    scanf("%s",new_node->id);
    printf("please input phone!\n");
    scanf("%s",new_node->phone);
    printf("please input home!\n");
    scanf("%s",new_node->home);
    printf("successfully added!\n");

    INFO * p;
    p = head;
    if(head == NULL)               //当通讯录为空时
    {
        head = new_node;
        new_node->next = NULL;
    }
    else                       //不为空
    {
        while(p->next !=NULL)
        {
            p = p->next;
        }
        p->next = new_node;
        new_node->next = NULL;
    }
    return (head);
}
//删除联系人函数
INFO *del(INFO ** head)
{   
    char key[20];
    printf("please input name!\n");
    scanf("%s",key);

    INFO * p;
    INFO * q;
    p = *head;
    q = *head;  
    if(*head == NULL)            //当通讯录为空时
    {
    	 printf("***********************\n");
        printf("it is empty!\n");
    }
    else
    {
        if(0 == strcmp((*head)->name,key))         //当要是删除第一个联系人时
        {
            *head = (*head)->next;
            printf("delete sucessfully!\n");
            
        }
        else
        {
            while(p->next != NULL && 0 != strcmp(p->name,key))
            {
            	q = p;
            	p = p->next;
            }
            if(p->next ==NULL && 0 == strcmp(p->name,key))  //最后一个为要删除的人时
            {
            	q->next = NULL;
            	free(p);
            	printf("del sucessfully!\n");
            }
            if(p->next !=NULL&& 0 == strcmp(p->name,key)) //不是最后一个
            {
            	q->next = p->next;
            	free(p);
            	printf("del sucessfully!\n");
            }
            if(p->next !=NULL&& 0 != strcmp(p->name,key)) //找不到这样的人
            {
            	printf("no such person!\n");
            }
        }
        return *head;
    }   
}
	
//第二种方法
   /* INFO *p1;
    INFO *p2;
    p1 = head;
    p2 = head;
    if(head != NULL)
    {
        while(p1 !=NULL)
        {
            if(0 == strcmp(p1->name,key))
            {
                if(head != p1)
                {
                    p2->next = p1->next;
                }
                else
                {
                    head = p1->next;
                }
                free(p1);
                printf("delete sucessfully!\n");
                return head;
            }
            else
            {
                p2 = p1;
                p2->next = p1;
            }
        }
        printf("no such person!");
    }
    else
    {
        printf("it is empty!\n");
        return head;
    }
}*/
//修改联系人信息
INFO *modify(INFO *head)
{
	INFO *p, *q;
	char key[20];
	p = head;
    q = head;
	
	printf("please input name!\n");
	printf("****************************\n");
	scanf("%s",key);
	
	if(head != NULL)
	{
		while(p->next != NULL)
		{
			if(0 == strcmp(p->name,key))                           //非最后一个人是要修改的人时
			{
				printf("the perseon's info as follow：\n"); 
				printf("modify name %s:\n",p->name);
				scanf("%s",p->name);
				printf("modify id%s:\n",p->id);
				scanf("%s",p->id);
			    printf("modify phone%s:\n",p->phone);
			    scanf("%s",p->phone);
				printf("modify home%s:\n",p->home);
				scanf("%s",p->home);
				printf("\n");
				return head;
			}
			else
			{
				q = p;
				p = p->next;
			}
		}
		if(p->next ==NULL&& 0 == strcmp(p->name,key))     //最后一个人是要修改的人时
			{
			printf("the perseon's info as follow：\n");
				printf("modify name %s:\n",p->name);
				scanf("%s",p->name);
				printf("modify id%s:\n",p->id);
				scanf("%s",p->id);
			    printf("modify phone%s:\n",p->phone);
			    scanf("%s",p->phone);
				printf("modify home%s:\n",p->home);
				scanf("%s",p->home);
				printf("\n");
				return head;
			}
			else                                //找不到这样的人
				{
					printf("no such person\n");
				}
	
	}
	else       
	{
		printf("address_list is empty!\n");
	}
	
}
//查找联系人函数
INFO *search(INFO *head)
{
	INFO *p, *q;
	char key[20];
	p = head;
    q = head;
	
	printf("please input name!\n");
	printf("****************************\n");
	scanf("%s",key);
	
	if(head != NULL)            //当通讯录为空时
	{
		while(p->next != NULL)
		{
			if(0 == strcmp(p->name,key))      //非最后一个人是要查找的人时
			{
				printf("the perseon's info as follow：\n");  
				printf("name:%s\t",p->name);
				printf("id:%s\t",p->id);
				printf("phone:%s\t",p->phone);
				printf("home:%s\t",p->home);
				printf("\n");
				return head;
			}
			else
			{
				q = p;
				p = p->next;
			}
		}
		if(p->next ==NULL&& 0 == strcmp(p->name,key))  //最后一个人是要查找的人时
			{
				printf("the perseon's info as follow：\n");
				printf("name:%s\t",p->name);
				printf("id:%s\t",p->id);
				printf("phone:%s\t",p->phone);
				printf("home:%s\t",p->home);
				printf("\n");
				return head;
			}
			else                  //找不到这样的人
				{
					printf("no such person\n");
				}
	
	}
	else
	{
		printf("address_list is empty!\n");
	}
	
}



int main()
{
    int choose;
    INFO *head = NULL;
   
    //system("clear");
    
    while(1)
    {
        face();
        printf("please input your choose!\n");

        scanf("%d",&choose);
        switch(choose)
        {
            case 0:return 0;
            case 1:head = print(head);
                   break;
            case 2:head = add(head);
                   break;
            case 3:head = del(&head);
                   break;
            case 4:head = modify(head);
                   break;
            case 5:head = search(head);
                   break;
         	default:printf("input error!\n");
                   break;

        }

    }
    
}