6. What is the disadvantages of the low-level file I/O?

Ans:

The disadvantage of Low-Level Disk I/O functions is that the programmer has to manage the buffers.

Ex 1: What is the output?

#include "stdio.h"
main( )
{
 FILE *fp ;
 char c ;
 fp = fopen ( "TRY.C" ,"r") ;
if ( fp == null )
{
            puts ( "Cannot open file" ) ;
            exit( ) ;
}
while ( ( c = getc ( fp ) ) != EOF )
putch ( c ) ;
fclose ( fp ) ;
}

Ans:

compile time error

Explanation:
 The null is undefined literal in c. So compiler give the error. If u give NULL it is run successfully.

Ex 2: What is the output?

#include<stdio.h>
main( )
{
FILE *fp ;
char str[80] ;
fp = fopen ( "TRY.C", "r" ) ;
while ( fgets ( str, 80, fp ) != EOF )
fputs ( str ) ;
fclose ( fp ) ;
}

Ans:

Compiler error.

Explanation:

The fputs() in the above program hava only one argument.The syntax of  the fputs() have two argument. So fputs() call don’t match with definition of that function.