C Language | Set 8

Following questions have been asked in GATE CS 2011 exam.

1) What does the following fragment of C-program print?

filter_none

edit
close

play_arrow

link
brightness_4
code

char c[] = "GATE2011";
char *p =c;
printf("%s", p + p[3] - p[1]) ;

chevron_right


(A) GATE2011
(B) E2011
(C) 2011
(D) 011

Answer: (C)
See comments for explanation.

filter_none

edit
close

play_arrow

link
brightness_4
code

char c[] = "GATE2011";
 
 // p now has the base address string "GATE2011"
char *p =c; 
 
// p[3] is 'E' and p[1] is 'A'.  
// p[3] - p[1] = ASCII value of 'E' - ASCII value of 'A' = 4
// So the expression  p + p[3] - p[1] becomes p + 4 which is 
// base address of string "2011"
printf("%s", p + p[3] - p[1]) ; 

chevron_right




2) Consider the following recursive C function that takes two arguments

filter_none

edit
close

play_arrow

link
brightness_4
code

unsigned int foo(unsigned int n, unsigned int r) {
  if (n  > 0) return (n%r +  foo (n/r, r ));
  else return 0;
}

chevron_right


What is the return value of the function foo when it is called as foo(513, 2)?
(A) 9
(B) 8
(C) 5
(D) 2



Answer: (D)
foo(513, 2) will return 1 + foo(256, 2). All subsequent recursive calls (including foo(256, 2)) will return 0 + foo(n/2, 2) except the last call foo(1, 2) . The last call foo(1, 2) returns 1. So, the value returned by foo(513, 2) is 1 + 0 + 0…. + 0 + 1.
The function foo(n, 2) basically returns sum of bits (or count of set bits) in the number n.


3) What is the return value of the function foo when it is called as foo(345, 10) ?

(A) 345
(B) 12
(C) 5
(D) 3

Answer: (B)
The call foo(345, 10) returns sum of decimal digits (because r is 10) in the number n. Sum of digits for 345 is 3 + 4 + 5 = 12.

Please see GATE Corner for all previous year paper/solutions/explanations, syllabus, important dates, notes, etc.

Please write comments if you find any of the answers/explanations incorrect, or you want to share more information about the topics discussed above.



My Personal Notes arrow_drop_up


Article Tags :

Be the First to upvote.


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.