Files and Streams Easy Questions and Answers

What is the output of this program?

#include <iostream>
    int main ()
    {
        FILE * ptr;
        long size;
        ptr = fopen ("Example.txt", "rb");
        if (ptr == NULL) 
            perror ("Error opening file");
        else
        {
            fseek (ptr, 0, SEEK_END); 
            size = ftell (ptr);
            fclose (ptr);
            printf (" %ld\n", size);
        }
        return 0;
    }

Correct Option: A

This program will return the size of the file in bytes.

What is the output of this program in the file?

#include <iostream>
    int main ()
    {
        freopen ("Sample.txt", "w", stdout);
        printf ("This is redirected to a file");
        fclose (stdout);
        return 0;
    }

Correct Option: C

In this program, We are sending the text to the file by opening the file using the function freopen.

What is the output of this program?

#include <iostream>
    int main ()
    {
        int k;
        FILE * ptr;
        char buff[10];
        ptr = fopen ("Sample.txt", "w+");
        for ( k = 'A' ; k <= 'D' ; k++)
        fputc ( k, ptr);
        rewind (ptr);
        fread (buff, 1, 5, ptr);
        fclose (ptr);
        buff[3] = '\0';
        puts (buff);
        return 0;
    }

Correct Option: A

In this program, We are setting the buffer size upto 3 only, So it is printing ABC.

What is the output of this program in the text file?

#include 
    int main ()
    {
        FILE * ptr;
        char buff[] = { 'I' , 'L' , 'U' };
        ptr = fopen ( "Example.txt" , "wb" );
        fwrite (buff , 1 , sizeof(buff) , ptr );
        fclose (ptr);
        return 0;
    }

Correct Option: D

In this program, We are writing into the file by using the function fwrite.

By using which function does the buffer are automatically flushed?

Correct Option: A

fclose