嵌入式学习第十八天（目录IO）

本文主要是介绍嵌入式学习第十八天（目录IO），希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

目录IO:

1. mkdir

int mkdir(const char *pathname, mode_t mode);

功能：创建目录文件

参数：

pathname：文件路径

mode：文件的权限

rwx rwx rwx

111 111 111

0 7 7 7

r：目录中是否能够查看文件

w：目录中是否能够新建文件

x：目录是否能够进入

返回值：

成功返回0

失败返回-1

2. rmdir：

int rmdir(const char *pathname);

功能：删除空目录文件

返回值：

成功返回0

失败返回-1

3. opendir

DIR *opendir(const char *name);

参数：

name：目录文件路径

返回值：

成功返回目录流指针

失败返回NULL

4. closedir

int closedir(DIR *dirp);

功能：关闭目录流指针

5. readdir

struct dirent *readdir(DIR *dirp);

功能：从目录流中读取下一个目录项的结构体信息

参数：

dirp：目录流指针

返回值：

成功返回包含目录项信息的空间首地址
失败返回NULL
读到文件末尾返回NULL

struct dirent {ino_t          d_ino;       /* Inode number */off_t          d_off;       /* Not an offset; see below */unsigned short d_reclen;    /* Length of this record */unsigned char  d_type;      /* Type of file; not supportedby all filesystem types */char           d_name[256]; /* Null-terminated filename */};

6. chdir

int chdir(const char *path);

功能：切换当前代码的工作路径

7. getcwd

char *getcwd(char *buf, size_t size);

功能：获得当前目录的绝对路径

8. access

int access(const char *pathname, int mode);

功能：检测调用函数的程序对文件是否拥有指定权限

参数：

pathname：文件路径

mode：

R_OK 检测是否拥有读权限
W_OK 检测是否拥有写权限
X_OK 检测是否拥有执行权限
F_OK 检测文件是否存在

返回值：

有该权限返回0
出错返回-1

作业：

1. 执行两次代码，打印出两次执行过程中新增的文件及删除的文件

#include "head.h"int ListFile(const char *pdirname, const char *pfilename)
{FILE *fp = NULL;DIR *dp = NULL;struct dirent *pp = NULL;char tmpbuff[4096] = {0};fp = fopen(pfilename, "a");if(fp == NULL){perror("fail to fopen");return -1;}dp = opendir(pdirname);if(dp == NULL){perror("fail to opendir");return -1;}while(1){pp = readdir(dp);if(pp == NULL){break;}if(*pp->d_name == '.'){continue;}sprintf(tmpbuff, "%s/%s", pdirname, pp->d_name);fprintf(fp, "%s\n", tmpbuff);if(pp->d_type == DT_DIR){ListFile(tmpbuff, pfilename);}}fclose(fp);closedir(dp);return 0;
}int ListDir(const char *pdirname, const char *pfilename)
{FILE *fsrc = NULL;FILE *fdst = NULL;DIR *dp = NULL;struct dirent *pp = NULL;char tmpbuff[4096] = {0};char tmpsrc[4096] = {0};char tmpdst[4096] = {0};char *psrc = NULL;char *pdst = NULL;fsrc = fopen(pfilename, "r");if(fsrc == NULL){perror("fail to fopen");return -1;}fdst = fopen("b.txt", "w+");if(fdst == NULL){perror("fail to fopen");return -1;}dp = opendir(pdirname);if(dp == NULL){perror("fail to opendir");return -1;}ListFile(pdirname, "b.txt");fseek(fsrc, 0, SEEK_SET);fseek(fdst, 0, SEEK_SET);while(1){pdst = fgets(tmpdst, sizeof(tmpdst), fdst);if(pdst == NULL){break;}int found1 = 0;fseek(fsrc, 0, SEEK_SET);while(1){psrc = fgets(tmpsrc, sizeof(tmpsrc), fsrc);if(psrc == NULL){break;}if(strcmp(tmpsrc, tmpdst) == 0){found1 = 1;break;}}if(!found1){printf("add:%s\n", tmpdst);			}}fseek(fsrc, 0, SEEK_SET);fseek(fdst, 0, SEEK_SET);while(1){psrc = fgets(tmpsrc, sizeof(tmpsrc), fsrc);if(psrc == NULL){break;}int found2 = 0;fseek(fdst, 0, SEEK_SET);while(1){pdst = fgets(tmpdst, sizeof(tmpdst), fdst);if(pdst == NULL){break;}if(strcmp(tmpdst, tmpsrc) == 0){found2 = 1;break;}}if(!found2){printf("mul:%s\n", tmpsrc);}}fclose(fsrc);fclose(fdst);closedir(dp);return 0;
}int main(int argc, const char *argv[])
{int flat = 0;if(argc != 3){fprintf(stderr, "Usage:./a.out dirname filename\n");return -1;}flat = access(argv[2], F_OK);if(flat == 0){ListDir(argv[1], argv[2]);}else{ListFile(argv[1], argv[2]);}return 0;
}