单链表！！

#include"stdio.h"
#include"stdlib.h"
struct linknode
{
	int date;
	struct linknode *next;
};
struct linknode *creat()//建立链表
{
	struct linknode *head,*tail,*temp;
	int dates;
	head=temp=tail=NULL;
	while(scanf("%d",&dates)!=EOF)
	{
		temp=(struct linknode*)malloc(sizeof(struct linknode));
		if(temp==NULL)
			printf("allocate error!\n");
		else
		{
			temp->date=dates;
			temp->next=NULL;
			if(head==NULL)
				head=tail=temp;
			else
			{
				tail->next=temp;
				tail=temp;
			}
		}
	}
	return head;
}
void print(struct linknode *head)//打印链表
{
	struct linknode *p;
	p=head;
	while(p)
	{
		printf("%d ",p->date);
		p=p->next;
	}
}
struct linknode*find(struct linknode*head,int dates)//找特定值
{
	struct linknode *p;
	p=head;
	while(p->date!=dates&&p->next!=NULL)
	{
		p=p->next;
	}
	if(p->date==dates)
		return p;
	else
		return NULL;
}
struct linknode*findahead(struct linknode *head,int dates)//找特定值的前一个
{
	struct linknode *p,*q;
	p=head;
	q=NULL;
	while(p->date!=dates&&p->next!=NULL)
	{
		q=p;
		p=p->next;
	}
	if(p->date==dates)
		return q;
	else
		return NULL;
}
struct linknode *entertohead(struct linknode *head,int dates)//在头指针前加数据
{
	struct linknode *enter;
	enter=(struct linknode *)malloc(sizeof(struct linknode));
	if(enter==NULL)
		printf("allocate error!\n");
	enter->date=dates;
	enter->next=NULL;
	if(head==NULL)
		head=enter;
	else
	{
		enter->next=head;
		head=enter;
	}
	return head;
}
struct linknode *entertotail(struct linknode *head,int dates)//在链表尾加数据
{
	struct linknode *enter,*p;
	p=head;
	enter=(struct linknode*)malloc(sizeof(struct linknode));
	if(enter==NULL)
		printf("allocate error!\n");
	enter->date=dates;
	enter->next=NULL;
	if(head==NULL)
		head=enter;
	else
	{
		while(p->next)
		{
			p=p->next;
		}
		p->next=enter;
	}
	return head;
}
struct linknode *entertovalue(struct linknode*head,int value,int dates)//特定位置加节点
{
	struct linknode *enter,*fp,*p;
	p=findahead(head,value);
	fp=find(head,value);
	if(fp==NULL)
		printf("no number is value\n");
	enter=(struct linknode*)malloc(sizeof(struct linknode));
	enter->date=dates;
	enter->next=NULL;
	if(enter==NULL)
		printf("allocate error\n");
	else
	{
		if(fp==head)
		{
			enter->next=head;
			head=enter;
		}
		else
		{
			p->next=enter;
			enter->next=fp;
		}
	}
	return head;
}
struct linknode *delet(struct linknode *head,int dates)//删除节点
{
	struct linknode *delet,*p;
	p=findahead(head,dates);
	delet=find(head,dates);
	if(!delet)
		return NULL;
	else
	{
		p->next=delet->next;
		free(delet);
		return head;
	}
}
void main()//测试链表
{
	struct linknode *head,*fd;
	head=creat();
	print(head);
	fd=findahead(head,4);
	if(fd==NULL)
		printf("ahead of value is NULL.\n");
	else
		printf("\n%d\n",fd->date);
	print(head=entertohead(head,88));
	printf("\n");
	print(entertotail(head,77));
	printf("\n");
	head=delet(head,6);
	if(head)
		print(head);
	else
		printf("have no this number\n");
	printf("\n");
}