GATE | GATE-CS-2017 (Set 1) | Question 30
Consider the C code fragment given below.
typedef struct node
{
int data;
node* next ;
} node;
void join(node* m, node* n)
{
node* p = n;
while (p->next != NULL)
{
p = p->next;
}
p–>next = m;
}
Assuming that m and n point to valid NULL- terminated linked lists, invocation of join will
(A) append list m to the end of list n for all inputs
(B) either cause a null pointer dereference or append list m to the end of list n
(C) cause a null pointer dereference for all inputs.
(D) append list n to the end of list m for all inputs.
Answer: (B)
Explanation: As it is stated in the question, that m and n are valid Lists but not explicitly specified if the lists are empty or not. We can have two cases:
- Case 1: If lists are not NULL : Invocation of join will append list m to the end of list n if the lists are not NULL. For Example:Before join operation :
m =1->2->3->4->5->null
n =6->7->8->9->nullAfter join operation :
6->7->8->9->1->2->3->4->5->null
- Case 2: If lists are NULL :Â If the list n is empty and itself NULL, then joining and referencing would obviously create NULL pointer issue.
Therefore option B is correct
Quiz of this Question
Last Updated :
13 Aug, 2021
Like Article
Save Article
Share your thoughts in the comments
Please Login to comment...