Stack ,Heap & Priority Queue Jabeen Gull & Zeeshan Aslam Khan

7/31/2019 Stack ,Heap & Priority Queue Jabeen Gull & Zeeshan Aslam Khan

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Presentation

Topic

Stack ,Heap & Priority

Queue


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Presenters:

Jabeen GullMC113008

Zeeshan Aslam KhanMC113009


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Stack

The stack is a place in the computer memory

Where all the variables

that are declared and initialized

beforeruntime

are stored.


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Heap

The heap is the section ofcomputer memory

where all the variables

created orinitialized

at runtime

are stored.


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Memory segments

Text (Code) Segment

Stack Segment

Heap Segment


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What is stack?

The two sections other from the code segment in the

memory are used for data.

1. Automatic variables within functions.

2. Top of the stack


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What is heap?

On the other hand, heap is an area of memory used for

dynamic memory allocation. Blocks of memory are

allocated and freed in this case in an arbitrary order. The

pattern of allocation and size of blocks is not known until

run time. Heap is usually being used by a program

for many different purposes.


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Heap and stack from

programming perspectiveint x; /* static stack storage */

void main() {

int y; /* dynamic stack storage */

char str; /* dynamic stack storage */

str = malloc(50); /* allocates 50 bytes of dynamic

heap storage */

size = calcSize(10); /* dynamic heap storage */


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Scope: The stack is attached to a thread, so when the thread exits

the stack is reclaimed.

The heap is typically allocated at application startup bythe runtime, and is reclaimed when the application

(technically process) exits


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What determines the size of each of them?

The size of the stack is set when a thread is created.

The size of the heap is set on application startup, but can

grow as space is needed (the allocator requests morememory from the operating system).


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What makes one faster?

The stack is faster because the access pattern makes it

trivial to allocate and deallocate memory from it (a

pointer/integer is simply incremented or decremented),

while the heap has much more complex bookkeeping

involved in an allocation or free. Also, each byte in the

stack tends to be reused very frequently which means it

tends to be mapped to the processor's cache, making it

very fast.


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Why is stack and heap important?

When a program is loaded into memory, it takes some

memory management to organize the process. If memory management was not present in your computer

memory, programs would clash with each other leaving

the computer non-functional.


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Priority QueueA PriorityQueue is a data structure

that is designed to allow

efficient removal ofthe highest

Priority

item.
http://c2.com/cgi/wiki?PriorityQueuehttp://c2.com/cgi/wiki?PriorityQueue


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Priority QueueIn a simulation event queue, that would typically be the

event which happens next. Your linked list was in fact

such a queue. You removed an item, then added it with a

new priority. My point (if I had one) was that perhaps a

priority queue implementation existed for your use and

you didn't have to create anything. If there wasn't such a

thing, then you did


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PrioritiesHow to schedule and dispatch processes

Priorities quantify the relative importance of processes.

Static priorities

Dynamic priority


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Priority queue Example :

Doctor

FeverHeart Patient


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CodeRandom rand = new Random();

PriorityQueue queue = new PriorityQueue();

// initialize with 1000 elementsfor(int i=0; i

Stack ,Heap & Priority Queue Jabeen Gull & Zeeshan Aslam Khan

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