C语言 day21 | 我的日常分享

C语言 day21

发表于2020-05-27更新于2020-05-27字数统计818阅读时长10分

链表

链表的查询

main.c

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... ...
else if (strcmp(cmd, "search") == 0) {
			//printf("-------search--------\n");
			STU *res=NULL;
			char name[64]="";
			//memset(&res, 0, sizeof(STU));
			printf("请输入要查询的姓名：\n");
			scanf("%s", name);
			res = search_link(head,name);
			if (res == NULL)
			{
				printf("没有查到%s的有关信息\n",name);
			}
			else
			{
				printf("%s的信息：\n",name);
				printf("%d %s %f\n", res->num, res->name, res->score);
			}
		}
... ...

link.c

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//查询节点
STU* search_link(STU* head, char* name) {
	STU* pb = head;
	//判断链表是否存在
	if (pb == NULL) {
		printf("链表不存在\n");
		return head;
	}
	else
	{
		//寻找对应节点
		while (strcmp(pb->name, name) != 0 && pb->next != NULL) {//pb->next != NULL防止越界 出现段错误
			pb = pb->next;
		}

		//判断是否找到
		if (strcmp(pb->name, name) == 0)
		{
			return pb;
		}
		else
		{
			return NULL;
		}
	}
	
	//return pb;
}

链表节点的删除

main.c

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... ...
else if (strcmp(cmd, "delete") == 0) {
			//printf("-------delete--------\n");
			char name[64] = "";
			printf("请输入要删除的姓名：\n");
			scanf("%s", name);
			head = delete_link(head, name);//要更新链表头 所以要返回值 因为如果删除的是头节点链表头就更新了
		}

... ...

link.c

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STU* delete_link(STU *head, char *name) {
	STU* pb = head,*pf=head;//pf跟在pb后面 用于后面删除中部节点
	//判断链表是否存在
	if (pb == NULL) 
	{
		printf("链表不存在\n");
		return head;
	}
	else//链表存在
	{
		//寻找要删除节点
		while (strcmp(pb->name, name) != 0 && pb->next != NULL) //pb->next != NULL防止越界 出现段错误
		{
			pf = pb;
			pb = pb->next;
		}
		//判断删除节点是否存在
		if (strcmp(pb->name, name) == 0)//存在
		{
			//判断节点的位置
			if (pb == head)//头部
			{
				head = pb->next;
				free(pb);
				return head;
			}
			else if (pb->next!=NULL && pb!=head)//中部
			{
				pf->next = pb->next;
				free(pb);
			}
			else if (pb->next==NULL)//尾部
			{
				pf->next = NULL;
				free(pb);
			}
		}
		else//不存在
		{
			printf("%s节点不存在\n",name);
		}
	}
	return head;
}

释放链表

main.c

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else if (strcmp(cmd, "free") == 0) {
			//printf("-------free--------\n");
			char sure[8] = "";
			printf("确定要释放链表?(Y/N)");
			scanf("%s", sure);
			if(strcmp(sure,"Y")==0)
			{
				head = free_link(head);//别忘了更新链表头 链表释放完成后，链表头指向的还是原来的地址，所以要更新
			}
			else
			{
				continue;
			}
		}
··· ···

link.c

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//释放链表
STU* free_link(STU* head) {
	STU* pb = head,*head_tmp=head;
	//判断链表是否存在
	if (pb == NULL) //不存在
	{
		printf("链表不存在\n");
		return;
	}
	else//存在
	{
		while (pb!=NULL)
		{
			head_tmp = pb->next;
			free(pb);
			pb = head_tmp;
		}
		printf("链表释放完成！\n");
		return NULL;
	}
	return NULL;
}

链表的逆序

main.c

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else if (strcmp(cmd, "reserve") == 0)
		{
			//printf("-------reserve----------");
			head = reserve_link(head);
		}
··· ···

link.c

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//链表逆序
STU* reserve_link(STU* head) {
	//1、判断链表是否存在
	if (head == NULL)
	{
		printf("链表不存在！\n");
		return head;
	}
	else
	{
		STU* pb = head, * pr = head;
		pb = pb->next;
		head->next = NULL;

		while (pb != NULL)
		{
			pr = pb->next;//记录pb->next
			pb->next = head;
			head = pb;
			pb = pr;

		}
		return head;
	}
}

链表的整理

按学号进行排序
main.c

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else if (strcmp(cmd, "sort") == 0)
		{
			//printf("-------sort----------");
			head = sort_link(head);
		}
··· ···

link.c

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//链表的整理
STU* sort_link(STU* head) {

	//还没写呢~
	return head;
}

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