鏈表應用——按字母順序存儲並輸出某目錄下的子文件或子目錄名

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

#define OK 0
#define ERROR -1

typedef struct Node
{
	char *fileName;
	Node *next;
} Node;

//創建一個空鏈表
Node* createLinkList();
//把文件名按字母順序插入鏈表
int insertLinkList(Node *head, char *fileName);
//輸出整個目錄
void output(Node head);

int main()
{

	Node *head = createLinkList();
	DIR *pd = opendir("/etc");
	struct dirent *fileData = NULL;
	while ((fileData = readdir(pd)) != NULL)
	{
		if (fileData->d_name[0] == '.')
			continue;
		insertLinkList(head, fileData->d_name);

	}
	output(*head);
	return 0;
}

Node* createLinkList()
{
	Node *head = (Node *) malloc(sizeof(Node));
	if (!head)
	{
		printf("分配內存空間失敗，程序將退出\n");
		exit(EXIT_FAILURE);
	}
	head->next = NULL;
	return head;
}

int insertLinkList(Node *head, char *fileName)
{
	Node *p = head;

	while (p)
	{
		Node *newNode = (Node *) malloc(sizeof(Node));
		if (!newNode)
		{
			printf("分配內存空間失敗，程序將退出\n");
			exit(EXIT_FAILURE);
		}
		if (p->next)
		{
			if (strcmp(fileName, p->next->fileName) < 0)
			{
				newNode->fileName = fileName;
				newNode->next = p->next;
				p->next = newNode;
				return OK;
			}
			else
			{
				p = p->next;
				continue;
			}
		}
		else
		{
			newNode->fileName = fileName;
			newNode->next = p->next;
			p->next = newNode;
			return OK;
		}
	}
	return OK;
}

void output(Node head)
{
	Node *p = (&head)->next;
	while (p)
	{
		printf("%s\n", p->fileName);
		p = p->next;
	}
}