{{{ void freeList( struct n

Aricent Interview Question for Software Engineer / Developers

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16
Answers

void freeList( struct node *n )
{
	while( n )
	{????}
}

Which one of the following can replace the ???? for the function above torelease the memory allocated to a linked list?
Choice 1 	n = n->next;
		free( n );

Choice 2 	struct node m = n;
		n = n->next;
		free( m );

Choice 3 	struct node m = n;
		free( n );
		n = m->next;

Choice 4 	free( n );
		n = n->next;

Choice 5 	struct node m = n;
		free( m );
		n = n->next;

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Interview Type: Written Test

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Comment hidden because of low score. Click to expand.

of 2 vote

- A June 27, 2012 | Flag Reply

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of 0 votes

The third option in addition to 2 is also right
struct node* m = n;
free( n );
n = m->next;

- Siva Krishna June 28, 2012 | Flag

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of 0 votes

must never free memory before pointing the current node to next (or dereferencing.).

- A June 28, 2012 | Flag

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of 0 votes

can you tell me what is the difference between 2 and 5?

- tea June 29, 2012 | Flag

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of 0 votes

Sure. Both 3 and 5 free the memory the pointer points to before attempting to use that memory. Creating a backup of the pointer doesn't help because the backup still points to the same memory location. It's not the pointer that gets altered during a call to free() -- it's the memory it points to. 2 is the correct option, assuming we correct the first line to use a *: struct node* m = n;

- eugene.yarovoi June 29, 2012 | Flag

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of 0 vote

- Avi June 27, 2012 | Flag Reply

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of 0 votes

And here n should point to start first.

- Avi June 27, 2012 | Flag

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of 0 votes

also after while loop , *n = NULL else traversal will give runtime error

- vagrawal13 June 27, 2012 | Flag

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of 0 vote

2 if we include *.

- Aalok June 28, 2012 | Flag Reply

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of 0 vote

Actually, trick question. They're all wrong. Option 2 needs a star:

struct node* m = n;
n = n->next;
free( m );

- Anonymous June 28, 2012 | Flag Reply

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of 0 votes

Option 3 is also correct if we include *.

- Aashish June 28, 2012 | Flag

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of 0 votes

No, it's not. In 3, you would free the memory pointed to by both n and m before dereferencing it.

- eugene.yarovoi June 28, 2012 | Flag

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of 0 vote

All are incorrect ....

- Nitin Gupta iitian June 28, 2012 | Flag Reply

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of 0 votes

I think they forgot to put the stars on struct node m . 2 was probably the intended answer.

- eugene.yarovoi June 28, 2012 | Flag

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of 0 vote

chioce 2 is correct.........

- kiran July 01, 2012 | Flag Reply

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of 0 vote

choice 4 . is correct
because n is a pointer .. first freeing it and then assigning it a new address .. just like we do in deletion of a linked list .
Choice 1 is wrong as it is not saving the next node value .. and choice 2,3,5 are illogical as there is no point in assigning a pointer to a normal struct variable for memory freeing purpose only .

- xenon August 11, 2013 | Flag Reply

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