循環雙鏈表加目錄IO實現簡單的文件檢索

#include"stdio.h"
#include"stdlib.h"
#include"fcntl.h"
#include"dirent.h"
#include"string.h"

typedef struct doublelink
{
char name[20];
struct doublelink *front;
struct doublelink *frev;
}dl;

dl *head = NULL;
dl *last = NULL;

void dircreate()
{
DIR *mydir;
struct dirent *myitem;
mydir = opendir(".");
while( ( myitem = readdir(mydir) ) != NULL )
{
if( ( strcmp(myitem->d_name,".") == 0 ) || ( strcmp(myitem->d_name,"..") == 0) )
{
continue;
}
dl *p = (dl *)malloc(sizeof(dl));
if( head == NULL)
{
strcpy(p->name,myitem->d_name);
head = p;
head->front = NULL;
head->frev = head;
last = p;
}
else
{
strcpy(p->name,myitem->d_name);
last->frev = p;
p->front = last;
last = p;
last->frev = head;
}
}
head->front = last;
closedir(mydir);
}

void print()
{
dl *p = head;
while(p->frev != head)
{
printf("%s ",p->name);
p = p->frev;
}
printf("%s \n",p->name);
}

void printfile()
{
int x;
printf("請選擇功能\n");
printf("1上一個文件\n");
printf("2下一個文件\n");
printf("3退出\n");
dl *p = head;
printf("第一個文件爲: %s \n",p->name);
while(1)
{
printf("請輸入\n");
scanf("%d",&x);
switch(x)
{
case 1:
{
p = p->front;
printf("上一個文件爲: %s \n",p->name);
break;
}
case 2:
{
p=p->frev;
printf("下一個文件爲: %s \n",p->name);
break;
}
case 3:
{
printf("正常退出\n");
exit(0);
}
}
}
}

int main()
{
dircreate();
print();
printfile();
return 0;
}