stack underflow

Question

A stack of size (1 to N) and the initial position of top pointer is 0.
get(i,S) is aroutine to get ith element from stack 'S' with respect to top.
then,what is the underflow condition on stack to perform get() operation?
$A) top-i<N$
$B) top-i+1<=N$
$C) top-i<=0$
$D) top-i+1<=0$

Answer 1

Option D

Comments

everything seems to be correct, but when you push the element into the stack, why you leave $0$th Position empty? and what it is mean underflow occurs when top$==0??$

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A stack of size (1 to N) and the initial position of top pointer is $0.$
(i,S) is aroutine to put ith element into stack 'S' with respect to top.
then,what is the overflow condition on stack to perform put() operation?

I think Condition should be the same for this case??

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why you leave 0th Position empty?

 In general when we implement Stack using Array we initialize the top = -1

and if top == -1 [is the underflow condition]

what in the given question initially top  = 0 therefore whenever we want to push element to the stack we start from index = 1

 

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see my last comment similar for Overflow?

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overflow condition

if (top = = N )

printf("overflow");

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A stack of size (1 to N) and the initial position of top pointer is 0.0.
(i,S) is aroutine to put ith element into stack 'S' with respect to top.
then,what is the overflow condition on stack to perform put() operation?

I think Condition should be the same for this case??

we want to put more that (N+1) elemet so this is "Overflow"??

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Ohk now see

I give you a simple scenario for this

N = 4 (i = 1 to 4 )

initially top is at index = 0

insert (10) --- > top is at index = 1  array[1] =10

insert(20) ----- > top is at index = 2 array[2] = 20

insert(30) ------> top is at index = 3 array[3] = 30

insert(40) ------> top is at index = 4 array[4] = 40

Now capacity of stack is full right ??  now if you insert one more element it's overflow condition right ???

insert(50) ----> if(top == 4) then there's a overflow condition

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carefully go through my answer which is for underflow condition By taking any small example you could analyze it well !!

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i understand, can you give the condition for overflow as well?

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if (top = = N )

printf("overflow");

 already given brother 

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I want to answer in terms of $i$

I think if(top=N+1)??

Because (top==N) point the last element.

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PEEP FUNCTION -to fnd ith element  from top of stack without deleting it

to check stack underflow(top−i+1<=0)