Following questions have been asked in GATE CS 2010 exam.
1. What does the following program print?
#include<stdio.h>void f(int *p, int *q){ p = q; *p = 2;}int i = 0, j = 1;int main(){ f(&i;, &j;); printf("%d %d \n", i, j); getchar(); return 0;} |
(A) 2 2
(B) 2 1
(C) 0 1
(D) 0 2
Answer (D)
See below f() with comments for explanation.
/* p points to i and q points to j */void f(int *p, int *q){ p = q; /* p also points to j now */ *p = 2; /* Value of j is changed to 2 now */} |
2. What is the value printed by the following C program?
#include<stdio.h>int f(int *a, int n){ if(n <= 0) return 0; else if(*a % 2 == 0) return *a + f(a+1, n-1); else return *a - f(a+1, n-1);} int main(){ int a[] = {12, 7, 13, 4, 11, 6}; printf("%d", f(a, 6)); getchar(); return 0;} |
(A) -9
(B) 5
(C) 15
(D) 19
Answer (C)
f() is a recursive function which adds f(a+1, n-1) to *a if *a is even. If *a is odd then f() subtracts f(a+1, n-1) from *a. See below recursion tree for execution of f(a, 6).
.
f(add(12), 6) /*Since 12 is first element. a contains address of 12 */
|
|
12 + f(add(7), 5) /* Since 7 is the next element, a+1 contains address of 7 */
|
|
7 - f(add(13), 4)
|
|
13 - f(add(4), 3)
|
|
4 + f(add(11), 2)
|
|
11 - f(add(6), 1)
|
|
6 + 0
So, the final returned value is 12 + (7 – (13 – (4 + (11 – (6 + 0))))) = 15
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.
Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.
