Read many contents from the file

Usage of the fseek Function

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;
}
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Fseek () function usage

Call form:

# Include "stdio. H" Fseek (file type pointer FP, displacement, starting point );

Function: Place the FP-Related File Location pointer to a specified location.

Where,"Displacement"Is long data, which indicates the number of bytes that the position pointer moves relative to the" starting point. If the displacement is a positive value, it indicates moving from the start point to the end of the file. If the displacement is a negative value, it indicates moving from the start point to the end of the file.

"Start PointIt can only be one of the three symbol constants defined in stdio. h:

Start Point	Corresponding number	File Location
Seek_set	0	File start
Seek_cur	1	Current File Location
Seek_end	2	End of File

For example:

Fseek (FP, 50l, 0); or fseek (FP, 50l, seek_set );

It moves the position pointer to 50 bytes away from the file header.

Note: After fseek (FP, 0l, seek_end), the current pointer of the file will be the last position, so if you need to read it, it will be read from there