Standard I/O common functions and Linux folder action functions __oracle

Standard I/O (#include <stdio.h>)

1. file* fopen (const char *filename,const char *mode);

Parameters:

FileName: filename;

Mode: Pattern:

Text file	binary files	Significance
R	Rb	Read-only
W	Wb	Write only
A	Ab	Additional
r+	rb+	Change Mode Open
w+	wb+	Change the way to open and set the file length to zero
A +	ab+	Change the way to open, append after file

2. Reading and writing

size_t fread (void *ptr, size_t size, size_t nitem, file* stream);

size_t fwrite (void *ptr, size_t size, size_t nitem, file* stream);

Parameters:

PTR: string to store data

Size: Yes. Read length

Nitem: Number of operations

Stream: File pointer

3. Close the file

int Flose (file* stream);

4. Write data that is not written in the file stream to the file immediately

int fflush (FILE *stream);

5. Lseek in I/O

int fseek (FILE *stream, long intoffset, int whence);

Parameters:

Stream: File pointer;

Offset: The location where the file pointer is to be set;

Whence: Defines the use of offset values to remove the face value:

Seek_set	Offset is an absolute article
Seek_cur	Offset is a relative position relative to the current
Seek_end	Offset is a relative position relative to the end of the file

6. single fetch, input character

int fgetc (FILE *steam);

int getc (FILE *steam);

int GetChar ();

int FPUTC (FILE *steam);

int PUTC (FILE *steam);

int Putchar ();

7. Get String function

Char *fgets (char *s, int n, file* stream);

Char *gets (char *s);

Returns a pointer to S.

8. formatted input and output

int fprintf (FILE *stream, const char *format ...);

int printf (const char *format ...);

Sprint Int (char *s, const char*format ...);

int scanf (const char *format ...);

int fscanf (FILE *stream, const char *format ...);

int sscanf (char *s, const char*format ...);

9. File Stream Error

#include <errno.h>

int ferror (FILE *stream);

int feof (FILE *stream);

void clearer (FILE *stream);

String Copy

#include <string.h>

void*memcpy (void *dest, const void *SRC, size_t n);

function returns the value of the dest. directory operations (#include <sys/types.h> #include <dirent.h>)

Folder structure Body:

struct dirent{

ino_t D_ino; D_ino This directory into the point of the Inode

ff_t D_off; D_off the beginning of the directory file to the entry point in this directory

signed short int d_reclen; The length of the D_reclen _name, which does not contain null characters

unsigned char d_type; D_type D_name refers to the file type D_name file name

Char d_name[256]; Filename

};

In this section, refer to the file: "folder operation. docx"

1. Open, read, and close the directory

Dir*opendir (const char *name);

Structdirent *readdir (DIR *dirp);

Intclosedir (DIR *dirp);

2. return to current position

Long int telldir (DIR *dirp);

3. Set folder pointer

Void Seekdir (DIR *dirp, long int loc);

4. examples

#include <sys/types.h>

#include <dirent.h>

#include <unistd.h>

Main ()

{

dir * DIR;

struct dirent * PTR;

int i;

dir = Opendir ("/etc/rc.d");

while (ptr = Readdir (dir))!= NULL)

{

printf ("D_name:%s\n", ptr->d_name);

}

Closedir (dir);

}

5. Get folder details

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>

int stat (const char *path, Structstat *buf);

int fstat (int fd, struct stat*buf);

Intlstat (const char *path, struct stat *buf); When the path is a link, get the information for the link itself, not the file that the link points to.

Stat Structure Body:

struct STAT {

dev_t St_dev; /* ID of device containing file */

ino_t St_ino; /* Inode Number * *

mode_t St_mode; * Protection * *

nlink_t St_nlink; /* Number of hard links */

uid_t St_uid; /* User ID of owner/*

gid_t St_gid; /* Group ID of owner/*

dev_t St_rdev; /* Device ID (if special file) * *

off_t st_size; /* Total size, in bytes * *

blksize_t st_blksize; /*blocksize for file system I/O *

blkcnt_t st_blocks; /* Number of 512Bblocks allocated * *

time_t St_atime; /* Time of last access */

time_t St_mtime; /* Time of last modification*/

time_t St_ctime; /* Time of last status change * *

};

Attached: Judge file type:

Structstat Statbuf;

S_isreg (Statbuf.mode): Is it a regular file?

S_isdir (statbuf.mode): directory?

S_ISCHR (Statbuf.mode): Character device?

S_ISBLK (statbuf.mode): Block device?

S_isfifo (Statbuf.mode) FIFO: (nastatbuf.modeedpipe)?

S_islnk (statbuf.mode): Systatbuf.modebolic link? (Not inposix.1-1996.)

S_issock (Statbuf.mode): Socket? (not in posix.1-1996.)