Questions and answers for exam Preparation

MCQs

Total Questions : 35 | Page 1 of 4 pages

Can we specify a variable filed width in a scanf() format string?

Discuss Question

Answer: Option B. -> No

In scanf() a * in a format string after a % sign is used for the suppression of assignment. That is, the current input field is scanned but not STORED.

Question 2.

Will the following program work?

#include<stdio.h>
int main()
{
int n=5;
printf("n=%*d\n", n, n);
return 0;
}

Discuss Question

Answer: Option A. -> Yes

It prints n= 5

Question 3.

A file written in text mode can be read back in binary mode.

Discuss Question

Answer: Option B. -> No

The difference is that text files contain lines (or records) of text and each of these

has an end-of-line marker automatically appended to the end of it whenever you

indicate that you have reached the end of a line.

Binary files are not broken up into separate lines or records so the end-of line marker

is not written when writing to a binary file.

So, we cannot read the correct the data in binary mode.

Question 4.

stderr, stdin, stdout are FILE pointers

Discuss Question

Answer: Option A. -> Yes

Yes, these will be declared like

The corresponding stdio.h variable is FILE* stdin;

The corresponding stdio.h variable is FILE* stdout;

The corresponding stdio.h variable is FILE* stderr;

Question 5.

In a call to printf() function the format specifier %b can be used to print binary equivalent

of an integer.

True
False

Discuss Question

Answer: Option B. -> False

There is no format specifier named %b in c.

Question 6.

We should not read after a write to a file without an intervening call to fflush(), fseek()

or rewind()

True
False

Discuss Question

Answer: Option A. -> True

True, we should not be able to read a file after writing in that file without calling the below

functions.

int fflush ( FILE * stream ); If the given stream was open for writing and the last i/o operation

was an output operation, any unwritten data in the output buffer is written to the file.

int fseek ( FILE * stream, long int offset, int origin ); Its purpose is to change the file position

indicator for the specified stream.

void rewind ( FILE * stream ); Sets the position indicator associated with stream to the

beginning of the file.

Question 7.

Offset used in fseek() function call can be a negative number.

True
False

Discuss Question

Answer: Option A. -> True

True, offset in fseek() function can be a negative number. It makes the file pointer to

move backwards from the current position.

Declaration: retval = fseek( fp, offset, from );

Where:

FILE *fp; = points to the file on which I/O is to be repositioned.

long offset; = is an integer giving the number of bytes to move forward or backward in

the file. This may be positive or negative.

int from; = is one of the manifests SEEK_SET, SEEK_CUR, or SEEK_END.

int retval; = is non-zero if the seek operation was invalid (e.g. on a file not opened with

a "b" option); otherwise, the return value is zero.

Question 8.

A text stream is an ordered sequence of characters composed into lines, each line

consisting of zero or more characters plus a terminating new-line character.

True
False

Discuss Question

Answer: Option A. -> True

True, each line may contain zero or more characters terminated by a newline character.

Question 9.

Point out the correct statements about the program?

#include<stdio.h>
int main()
{
FILE *fptr;
char str[80];
fptr = fopen("f1.dat", "w");
if(fptr == NULL)
printf("Cannot open file");
else
{
while(strlen(gets(str))>0)
{
fputs(str, fptr);
fputs("\n", fptr);
}
fclose(fptr);
}
return 0;
}