Iseek$()-$ Syntax

The lseek$()$ system call is used to change the position of the file offset $($or file pointer$)$ within an open file. This file offset

determines where in the file the next read or write operation will start. By using lseek$(),$ you can move the file pointer to

different positions within the file, allowing you to read or write data at specific locations.

Syntax : off$\_$t lseek$($int fd$,$ off$\_$t offset, int whence$)$;

$$ fd: The file descriptor of the open file. This is the integer value returned by the open$()$ system call.

$$ offset: The number of bytes by which the file pointer should be moved. This can be a positive or negative value depending

on the direction in which you want to move the pointer.

$$ whence: This parameter specifies the reference point from which the offset is applied. It can have one of the following

values:

Examples:

$$ lseek$($fd$,5,$ SEEK$\_$SET$)$ This shifts the file pointer $5$ positions forward, starting from the beginning of the file.

$$ lseek$($fd$,5,$ SEEK$\_$CUR$)$ This moves the file pointer $5$ positions forward from its current location in the file.

$$ lseek$($fd$,-5,$ SEEK$\_$CUR$)$ This shifts the file pointer $5$ positions backward from its current position in the file.

$$ lseek$($fd$,-5,$ SEEK$\_$END$)$ This moves the file pointer $5$ positions backward from the end of the file

using thia concepts and give me the correct code for the below questions.

Q$1.$ Write a program to print characters starting from $15$th character

till the $20$th character of file F$1.$txt into file F$4.$txt$.$

$$ Q$2.$ Write a program to print the last $5$ characters of a file.

$$ Q$3.$ Write a program to read a number$($n$)$ from the user. Print the first

n characters from the file F$1.$txt$.$

$$ Q$4.$ Write a program to print the second half of a file.

$$ Q$5.$ Write program$($s$)$ to show the use of SEEK$\_$SET, SEEK$\_$CUR and

SEEK$\_$END