链表的简单处理

#include<stdio.h>
#include<stdlib.h>
#define LEN sizeof(struct Student)
struct Student{
	long no;
	float score;
	struct Student *next;
};
int n;
//动态建立链表 
struct Student *creat(void){
	struct Student *head;
	struct Student *p1,*p2;
	n=0;
	p1=p2=(struct Student *)malloc(LEN);
	printf("请输入链表元素（两组数据之间以空格分开,以0结束）:");
	scanf("%ld %f",&p1->no,&p1->score);
	head = NULL;
	while(p1->no!=0){
		n=n+1;
		if(n==1){
			head = p1;
		}
		else p2->next=p1;
		p2=p1;
		p1=(struct Student *)malloc(LEN);
			printf("请输入链表元素（两组数据之间以空格分开,以0结束）:");
		scanf("%ld %f",&p1->no,&p1->score);
	}
	p2->next=NULL;
	return (head);
}
//打印链表 
void print(struct Student *head){
	struct Student *p;
	printf("\nThese %d recodes are:\n",n);
	p=head;
	if(head!=NULL){
		do{
			printf("%ld %5.1f\n",p->no,p->score);
			p=p->next;
		}while(p!=NULL);
	}
}
//删除链表中的某项
struct Student *delete(struct Student *head){
	struct Student *p, *temp;int i=0,count;
	printf("请输入删除位置:");
		scanf("%d",&count);
		if(count<=n){
		if(head!=NULL){
		do{
			i++;
			if(count==1&&i==count){
			head = head->next;	
			p = head;
			}else{
			if(i==count){
			temp = p->next;
		    p->next= temp->next;
		    n--;
			free(temp);	
			} else{
				if(i==1) p = head;
				else p=p->next;
			}	
			}
}while(p!=NULL);
	}	
	}else{
		printf("你输入的位置不存在！");
	}
	return (head);
}
//在链表中添加
struct Student *add(struct Student *head){
	struct Student *p, *temp; int i=0,count;
	printf("请输入插入位置:");
		scanf("%d",&count);
		if(count<=n){
		temp = (struct Student *)malloc(LEN);
		if(head!=NULL){
		do{
			if(count==0&&i==count){
				printf("请输入链表元素:");
		        scanf("%ld %f",&temp->no,&temp->score);
				temp->next=head;
				head=temp;
				n++;
			}else{
				if(i==count){
				printf("请输入链表元素:");
		        scanf("%ld %f",&temp->no,&temp->score);
		        temp->next=p->next;
				p ->next=temp;
				n++;
				p=temp;
			} else{
				if(i==0) 	p = head;
				else p=p->next;
			}
			}
			i++;
		}while(p!=NULL);
	}
	}else{
		printf("你输入的位置不存在！");
		}
		return (head);
} 
//打印指定位置链表元素
void check(struct Student *head){
	struct Student *p, *temp; int i=0,count;
	printf("请输入制定位置:");
	scanf("%d",&count);
	if(count<=n){
		printf("\nThe recode is:\n");
	p = head;
	if(head!=NULL){
		do{
			i++;
			if(i==count){
					printf("%ld %5.1f\n",p->no,p->score);
					break;
			}
			p=p->next;
		}while(p!=NULL);
	}
		}
	else{
		printf("你输入的位置不存在！");	
		}	
	
} 
menu(){
	printf("======菜单======\n");
	printf("1.打印链表元素\n");
	printf("2.打印指定位置的元素\n");
	printf("3.插入元素(在输入的位置之后)\n");
	printf("4.删除元素\n"); 
	printf("5.重置链表\n"); 
	printf("0.退出\n"); 
	printf("================\n");
}

//主函数 

 
int main()
{
struct Student *head;int j;
head=creat();
while(1){
	menu();
	scanf("%d",&j);
	switch(j){
		case 1: print(head); 
		break;
		case 2: check(head);
		break;
		case 3: head=add(head); 
		break;
		case 4: head=delete(head); 
		break;
		case 5: head = creat();
		break; 
		case 0: exit(0);
		defalut :
		printf("你的选择无效，请再次选择!");
		break;	 
	}
}
return 0;	
}