c语言系统编程三：文件目录操作

• 一 打开目录，获取该目录的结构体指针
• 二 读取目录下的文件或目录（调用一次只能读取一个文件）
• 三 关闭目录
• 四 递归扫描目录代码

1. 需要的头文件和函数原型

#include 
#include 
DIR *opendir(const char *name);

2. 功能
   打开一个文件目录
3. 参数：

name: 目录名

4. 返回值：

   成功：返回指向该目录的结构体指针
   失败：NULL

5. 代码

DIR *p = opendir("./");
        if(NULL == p)
        {
                perror("opendir");
                return 0;
        }

1. 需要的头文件和函数原型

#include 
struct dirent *readdir(DIR *dirp);

2. 功能
   读取目录，调用一次只能读取目录中一个文件或目录
3. 参数：

dirp：opendir的返回值

4. 返回值：

   成功：dirent结构体指针
   失败：NULL

5. dirent结构体定义：

struct dirent {
               ino_t          d_ino;       
               off_t          d_off;       
               unsigned short d_reclen;    
               unsigned char  d_type;      
               char           d_name[256]; 
           };

6. dirent结构体中d_type的解析
   
7. 代码

struct dirent *dp = NULL;
        while(dp = readdir(p))
        {
                if((dp->d_type & DT_REG) == DT_REG)
                        printf("%s是一个普通文件n",dp->d_name);
                else if((dp->d_type & DT_DIR) == DT_DIR)
                        printf("%s是一个目录n",dp->d_name);
        }   

1. 需要的头文件和函数原型

#include 
#include 

int closedir(DIR *dirp);

2. 功能：关闭目录
3. 参数：

dirp：opendir函数返回的指针

4. 返回值

成功：0
失败：-1

5. 代码

closedir(p);

[root@ansible9 ~]# cat 1.c
#include 
#include 
#include 
#include
void search_dir(const char* path)
{
	DIR *dir = opendir(path);
	if(NULL == dir)
	{
		perror("opendir");
		printf("%s报错n",path);
		return;
	}

	struct dirent *res = NULL;
	while(res = readdir(dir))
	{
		if((res->d_type & DT_REG) == DT_REG)
		{
			char filename[12800] = "";
			strncpy(filename,res->d_name,strlen(res->d_name));
			char filepath[12800] = "";
			strncpy(filepath,path,strlen(path));
			strcat(filepath,filename);
			printf("%s是一个普通文件n",filepath);
		}
		else if((res->d_type & DT_BLK) == DT_BLK)
		{
			char filename[12800] = "";
			strncpy(filename,res->d_name,strlen(res->d_name));
			char filepath[12800] = "";
			strncpy(filepath,path,strlen(path));
			strcat(filepath,filename);
			printf("%s是一个块设备文件n",filepath);
		}
		else if((res->d_type & DT_CHR) == DT_CHR)
		{
			char filename[12800] = "";
			strncpy(filename,res->d_name,strlen(res->d_name));
			char filepath[12800] = "";
			strncpy(filepath,path,strlen(path));
			strcat(filepath,filename);
			printf("%s是一个字符设备文件n",filepath);
		}
		else if((res->d_type & DT_FIFO) == DT_FIFO)
		{
			char filename[12800] = "";
			strncpy(filename,res->d_name,strlen(res->d_name));
			char filepath[12800] = "";
			strncpy(filepath,path,strlen(path));
			strcat(filepath,filename);
			printf("%s是一个管道文件n",filepath);
		}
		else if((res->d_type & DT_LNK) == DT_LNK)
		{
			char filename[12800] = "";
			strncpy(filename,res->d_name,strlen(res->d_name));
			char filepath[12800] = "";
			strncpy(filepath,path,strlen(path));
			strcat(filepath,filename);
			printf("%s是一个链接文件n",filepath);
		}
		else if((res->d_type & DT_SOCK) == DT_SOCK)
		{
			char filename[12800] = "";
			strncpy(filename,res->d_name,strlen(res->d_name));
			char filepath[12800] = "";
			strncpy(filepath,path,strlen(path));
			strcat(filepath,filename);
			printf("%s是一个socket文件n",filepath);
		}
		else if((res->d_type & DT_DIR) == DT_DIR)
		{
			char dirname[12800] = "";
			strncpy(dirname,res->d_name,strlen(res->d_name));
			char dirpath[12800] = "";
			strncpy(dirpath,path,strlen(path));
			//char dir_full_path[12800] = "";
			//sprintf(dir_full_path,"%s/%s",dirpath,dirname);
			strcat(dirpath,dirname);
			printf("%s是一个目录=============================n",dirpath);
			if((strcmp(dirname,".") == 0) || (strcmp(dirname,"..") == 0))
			{
				printf("%s跳过=============================n",dirpath);
			}
			else
			{
				strncat(dirpath,"/",1);
				search_dir(dirpath);
			}

		}
		else
		{
			char filename[12800] = "";
			strncpy(filename,res->d_name,strlen(res->d_name));
			char filepath[12800] = "";
			strncpy(filepath,path,strlen(path));
			strcat(filepath,filename);
			printf("%s是一个未知类型文件n",filepath);
		}
	}	
	closedir(dir);
	return;

}

int main(int arg,char *args[])
{
	search_dir("./");
}