Linux application Development-file programming-Library functions

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C library function file operation is independent of the specific system platform, the portability is good.

Library functions-Create and open

File*fopen (const char*filename,const Char*mode)

Mode: Open modes

Common open Mode:

R,RB: Read-only mode open

W,WB: Write-only open, if the file does not exist, create the file

A,ab: Append mode open, if file does not exist, create the file

r+,r+b,rb+: Read and write mode open

w+,w+b,wh+: Read and write mode open, if the file does not exist, create the file

a,a+b,ab+: Read and append mode open, if the file does not exist, create the file

B is used to differentiate between binary and text files, which is differentiated in Dos,window, where Linux does not differentiate between binary file box text files.

Library functions-Read

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

Reads n fields from a file pointed to by stream, each field is a size byte, and puts the read data into a character array referred to by PTR, returning the actual number of bytes read.

Library Functions-Write

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

Read characters:

int fgetc (file*stream);

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C library function file operation is independent of the specific system platform, the portability is good.

Library functions-Create and open

File*fopen (const char*filename,const Char*mode)

Mode: Open modes

Common open Mode:

R,RB: Read-only mode open

W,WB: Write-only open, if the file does not exist, create the file

A,ab: Append mode open, if file does not exist, create the file

r+,r+b,rb+: Read and write mode open

w+,w+b,wh+: Read and write mode open, if the file does not exist, create the file

a,a+b,ab+: Read and append mode open, if the file does not exist, create the file

B is used to differentiate between binary and text files, which is differentiated in Dos,window, where Linux does not differentiate between binary file box text files.

Read

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

Write:

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

Read characters

int fgetc (file*stream);

Example:

#include <stdio.h>

Main ()

{

FILE*FP;

Char ch;

if ((Fp=fopen ("C1.txt", "RT")) ==null)

{

printf ("\ncannot open file strike any key exit");

Getch ();

Exit (1);

}

CH=FGETC (FP);

while (CH!=EOP)

{

Putchar (CH);

CH=FGETC (FP);

}

Fclose (FP);

}

Write character

int fputs (Inyt c,file*stream)

Example:

#include <stdio.h>

Main ()

{

FILE*FP;

Char ch;

if ((Fp=fopen ("string", "w+")) ==null)

{

printf ("\ncannot open file, strike any key exit");

Getch ();

Exit (1);

}

printf ("Input a string:\n");

Ch=fgetchar ();

while (ch!= ' \ n ')

{

FPUTC (CH,FP);

Ch=getchar ();

}

printf ("\ n");

Fclose (FP);

}

Format read:

FSCANF (File*stream,char*format[,argument ...])

Format input from a stream

#include <stdlib.h>

#include <stdio.h>

int mian (void)

{

int i;

printf ("Input an Interger:");

if (fscanf (stdin, "%d", &i))

printf ("The integer read was:%i\n", i);

　　

}

Format write:

fprintf (File*stream,char*format[,argument ...])

Format the output from one stream

#include <stdlib.h>

#include <process.h>

File*stream;

int mian (void)

{

int i=10;

Double fp=1.5;

Char s[]= "This is a string";

Char c= ' \ n ';

Stream=fopen ("Fprintf.out", "" W);

fprintf (Stream, "%s%c", s,c);

fprintf (Stream, "%d\n", I);

fprintf (Stream, "%f\n", FP);

Fclose (stream);

　　

}

Positioning:

int fseek (File*stream,long offset,int whence);

Whence:

Seek_set

Seek_cur

Seek_end

Path obtained:

CHAR*GETCWD (char*buffer,size_t size);

Copy the path to buffer, if buffer is too small, return-1;

To create a directory:

int mkdir (char*dir,int mode);

0 returns success, 1 indicates an error.

Linux application Development-file programming-Library functions