C语言实现链表

    最近闲暇之际，重新看了一下C语言和数据结构，感觉链表很有意思，按照书上的思路自己写了一个重新，实现单向链表的操作，支持增加，删除，查找，读文件操作。先自己保留着，以后用的时候参考。

 

/* 
 * @author: lizhenbin
 * @date: 2011-09-14
 * @descrption: list operation
 */
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#define NULL 0

/* define a link node strut */
struct student 
{
	long num;
	struct student *prior; /* define point to the struct */
	struct student *next;
};

/* create struct */
struct student *create()
{
	struct student *head; /* link head and node point */
	struct student *p;
	struct student *q;
	long x;

	head = (struct student*)malloc(sizeof(struct student));
	q = head;
	head->next = NULL;
	printf("\nPlease input node numbers to the list: \n");
	scanf("%ld",&x);
	while(x!=0) 
	{
		/* create node */
		p = (struct student*)malloc(sizeof(struct student));
		p->num = x;
		p->next = NULL;
		q->next = p;
		p->prior = q;
		q = p;
		scanf("%ld",&x);
	}
	return head;
}

/* Output list all datas */
void print(struct student *head)
{
	struct student *p;
	p = head->next;
	printf("\nThe list is: ");
	if(p==NULL) 
	{
		printf("\nInput list is NULL!");
	}
	while(p!=NULL) 
	{
		printf("%ld ", p->num);
		p = p->next;
	}
	printf("\n");
}

/* delete list node */
void del(struct student *head)
{
	struct student *p;
	struct student *q;
	int i;
	int j=0;

	printf("Please input delete position: ");
	scanf("%d", &i);
	if(i<1) 
	{
		printf("You input %d error.", i);
		printf("\nTry again, Input nnum: ");
		scanf("%d", &i);
	}
	p = head;
	while(j<=i-1 && p!=NULL) 
	{
		p = p->next;
		j++;
	}
	if(p==NULL)
	{
		printf("\nThere is no %d in the list.", i);
		exit(1);
	}
	else
	{
		/* delete list node */
		q = p;
		p->prior->next = p->next;
		p->next->prior = p->prior;
		p = p->next;
		free(q);
	}
}

/* insert list node */
void insert(struct student *head)
{
	struct student *p;
	struct student *q = head;
	int i;
	int j = 0;
	
	p = (struct student*)malloc(sizeof(struct student));
	printf("\nPlease input the student No you want to insert: ");
	scanf("%ld", &p->num);
	printf("\nInput the student %d position to insert: ",p->num);
	scanf("%d", &i);
	if(i<1) 
	{
		printf("\nYou input %d error.", i);
		printf("\nTry again, Input nnum: ");
		scanf("%d", &i);
	}
	while(j<=i-1 && q->next!=NULL) 
	{
		q = q->next;
		j++;
	}
	if(q->next==NULL && j!=i)
	{
		p->next = NULL;
		p->prior = q;
		q->next = p;
	}
	else
	{
		q->prior->next = p;
		p->prior = q->prior;
		p->next = q;
		q->prior = q;
	}
}

/* search list node position and data */
void search(struct student *head)
{
	struct student *p;
	long number, i=1, j=0;

	printf("\nPlease input the index you want to search: ");
	scanf("%d", &number);
	p = head->next;
	printf("\nThe number in the list position is: ");

	while(p!=NULL)
	{
		if(p->num==number)
		{
			printf("%d\n",i);
			j = 1;
		}
		p = p->next;
		i++;
	}
	if(j==0) 
	{
		printf("There is no %ld in the list.\n",number);
	}
}

/* read data from file input */
struct student *filein() 
{
	struct student *p1;
	struct student *p2;
	struct student *head;
	int i = 0;
	FILE *fp;

	char file[20] = "d:/list/node.txt";
	printf("\nFileName is: %s\n", file);
	if((fp=fopen(file, "r"))==NULL)
	{
		printf("Can not open file: %s", file);
		exit(0);
	}
	p2 = (struct student*)malloc(sizeof(*p1));
	head = p2;
	p1 = (struct student*)malloc(sizeof(*p1));
	while(fread(p1, sizeof(*p1), 1, fp)==1)
	{
		i++;
		p2->next = p1;
		p2 = p1;
		p1->next = NULL;
		p1 = (struct student*)malloc(sizeof(*p1));
	}
	free(p1);
	fclose(fp);
	if(i==0)
	{
		printf("\nNo recored in %s ", file);
	}
	return head;
}

/* save the list result to file */
void savefile(struct student* head)
{
	struct student *p1;
	FILE *fp;
	char file[20] = "d:/list/node.txt";
	printf("\nFileName: %s", file);
	printf("\nPlease wait.../n");
	if((fp=fopen(file,"w"))==NULL)
	{
		printf("\nCan not open file: %s", file);
		exit(0);
	}
	p1 = head->next;
	while(p1!=NULL)
	{
		fwrite(p1, sizeof(struct student), 1, fp);
		p1 = p1->next;
	}
	fclose(fp);
}

/* print the operate menu */
void showMenu()
{
	printf("|-------------------------------------------------|\n");
	printf("|            Link List Opearte Menu               |\n");
    printf("|-------------------------------------------------|\n");
	printf("|                 1: Insert                       |\n");
	printf("|                 2: Delete                       |\n");
	printf("|                 3: Search                       |\n");
	printf("|                 4: FileIn                       |\n");
    printf("|                 5: Savefile                     |\n");
	printf("|                 6: Print List                   |\n");
	printf("|                 7: Print Menu                   |\n");
	printf("|                 8: Exit                         |\n");
	printf("|-------------------------------------------------|\n");
}

/* main funtion */
void main()
{
	int a=0;
	struct student *la;
	la = create();
	/*
	la = (struct student*)malloc(sizeof(struct student));
	la->next = NULL;
	*/
	while(1)
	{
		showMenu();
		scanf("\n%d", &a);
		switch(a)
		{
			case 1: insert(la); break;
			case 2: del(la); break;
			case 3: search(la); break;
			case 4: filein(); break;
			case 5: savefile(la); break;
			case 6: print(la); break;
			case 7: showMenu(); break;
			case 8: exit(1);
			default: printf("\nInput error,Try again.");break; 
		}
	}
}