How to use fseek?

小猪哼哼

How to use fseek?
Using fseek (fp, 1000,1,0);
Why do I keep getting errors?
Can't FSEEK be used under VC?
Thank you!

wownpc

How can fseek have four parameters?

fangjiehong

int fseek( FILE *stream, long offset, int origin );

Example

/* FSEEK.C: This program opens the file FSEEK.OUT and
* moves the pointer to the file's beginning.
*/

#include <stdio.h>

void main( void)
{
   FILE *stream;
   char line[81];
   int result;

   stream = fopen( "fseek.out", "w+" );
   if( stream == NULL)
      printf( "The file fseek.out was not opened\n" );
   else
   {
      fprintf( stream, "The fseek begins here: "
                       "This is the file'fseek.out'.\n" );
      result = fseek( stream, 23L, SEEK_SET);
      if( result)
         perror( "Fseek failed" );
      else
      {
         printf( "File pointer is set to middle of first line.\n" );
         fgets( line, 80, stream );
         printf( "%s", line );

      }
      fclose( stream );
   }
}

orangedj

man fseek

viva0329

int fseek( FILE *stream, long offset, int origin );

origin=0 first file
origin=1 current location
origin=2 end of file

offset is the number of origin bytes in distance

qingclie

You should install msdn

qingclie

linux directly man is ok

zjwzjw

Function name: fseek
Function: Relocate the file pointer on the stream
Usage: int fseek(FILE *stream, long offset, int fromwhere);
Program example:

#include <stdio.h>

long filesize(FILE *stream);

int main(void)
{
   FILE *stream;

   stream = fopen("MYFILE.TXT", "w+");
   fprintf(stream, "This is a test");
   printf("Filesize of MYFILE.TXT is %ld bytes\n", filesize(stream));
   fclose(stream);
   return 0;
}

long filesize(FILE *stream)
{
   long curpos, length;

   curpos = ftell(stream);
   fseek(stream, 0L, SEEK_END);
   length = ftell(stream);
   fseek(stream, curpos, SEEK_SET);
   return length;
}

kingtam03

fseek parameter error, usage:
  #include"stdio.h"
  fseek (file type pointer fp, displacement, starting point);
among them:

Starting point The corresponding number The file position

SEEK_SET 0 beginning of file
To

SEEK_CUR 1 Current location of the file
To

SEEK_END 2 End of file