C Programming Multiple Choice Questions and Answers on Line Input & Output in Files for Freshers

1. The syntax of fgets is char *fgets(char *line, int maxline, FILE *fp).which is true for     fgets.fgets

a) returns line on success
b) On end of file or error it returns NULL
c) Nothing
d) Both returns line on success & On end of file or error it returns NULL

Answer: d

2. fputs function writes a string to a file that only ends with a newline.

a) true
b) false
c) Depends on the standard
d) Depends on the compiler

Answer: b

3. What is the output of this C code?

1.     #include 

2.     #include 

3.     int main()

4.     {

5.         char line[3];

6.         fgets(line, 3, stdin);

7.         printf("%d\n", strlen(line));

8.         return 0;

9.     }

a) 3
b) 1
c) Any length since line did not end with null character
d) Depends on the standard

Answer: b

4. What is the output of this C code?

1.     #include 

2.     #include 

3.     int main()

4.     {

5.         char line[3];

6.         FILE *fp;

7.         fp = fopen("newfile.txt", "r");

8.         while (fgets(line, 3, fp))

9.         fputs(line, stdout);

10.         return 0;

11.     }

a) Compilation error
b) Infinite loop
c) Segmentation fault
d) No.of lines present in file newfile

Answer: c

5. What is the output of this C code if 2 character is typed by the user?

1.     #include 

2.     #include 

3.     int main()

4.     {

5.         char line[3];

6.         fgets(line, 3, stdin);

7.         printf("%d\n", line[2]);

8.         return 0;

9.     }

a) Compilation error
b) Undefined behaviour
c) 0
d) 10(ascii value of newline character)

Answer: c

6. fputs adds newline character

a) True
b) False
c) Depends on the standard
d) Undefined behaviour

Answer: b

7. puts function adds newline character

a) True
b) False
c) Depends on the standard
d) Undefined behaviour

Answer: a

8. gets function checks overflow run

a) True
b) False
c) Depends on the standard
d) Depends on the compiler

Answer: b

9. puts does the following when it writes to stdout

a) Deletes everything
b) Adds ‘t’ to the line written
c) Deletes the terminating ‘n’
d) Adds ‘n’ to the line written

Answer: d

10. What is the size of array “line” used in fgets(line, maxline, *fp) function?

a) maxline – 1
b) maxline
c) maxline + 1
d) Size is dynamic

Answer: b

11. The following function
    int fputs(char *line, FILE *fp)
    returns EOF when:

a) ‘�’ character of array line is encountered
b) ‘n’ character in array line is encountered
c) ‘t’ character in array line is encountered
d) When an error occurs

Answer: d

12. Identify X library function for line input and output?

1.     #include 

2.     int X(char *s, FILE *iop)

3.     {

4.         int c;

5.         while (c = *s++)

6.         putc(c, iop);

7.         return ferror(iop) ? EOF : 0;

8.     }

a) getc
b) putc
c) fgets
d) fputs

Answer: d

13. Which function has a return type as char pointer?

a) getline
b) fputs
c) fgets
d) All of the mentioned

Answer: c

14. Which of the following is the right declaration for fgets inside the library?

a) int *fgets(char *line, int maxline, FILE *fp);
b) char *fgets(char *line, int maxline, FILE *fp);
c) char *fgets(char *line, FILE *fp);
d) int *fgets(char *line, FILE *fp);

Answer: b

15. Which is true about fputs.fputs returns?

a) EOF if an error occurs
b) Non-negative if no error
c) EOF if an error occurs & Non-negative if no error
d) None of the mentioned

Answer: c

16. gets and puts operate on

a) stdin and stdout
b) files
c) stderr
d) nothing

Answer: a

17. gets does the following when it reads from stdin

a) Deletes the ‘t’
b) Puts adds it.
c) Deletes the terminating ‘n’
d) Nothing

Answer: c