Stack and Queue in Data Structures


Stack

In Data Structure, a stack is defined as a linear structure in which certain order of operations are performed.
The aforementioned operators will most likely include:
  •       Push: The addition of an item to a stack. If the stack is full, an Overflow condition is ruled        should you use the push operator on it.
  •     Pop: The removal of an item from a stack. If the stack is empty, an Underflow condition is        ruled should you use the pop operator on it.
  •       Peek/Top: Returning the top element of a stack.
  •       isEmpty: Checking whether or not a stack is empty.




In a stack, this order can either be LIFO (Last In First Out) or FILO (First In Last Out) because they are basically the same things. LIFO or FILO basically means that, in a list of items, the last one to be added will be taken out first. An example of this would be a stack of plates you have just washed and placed in a dryer. To put it back to the cupboard, you would use the LIFO method in which the latest washed plate gets taken first out of the stack.

Queue

Similar to a Stack, a Queue is also defined as a linear structure with a certain order of operations performed on them. The difference between a Stack and a Queue are the operations done to each of them and the order in which they are performed.
Operations in a queue usually include:
·           Enqueue: The addition of an item to a queue. Similar to a stack, an Overflow condition will be ruled if you use enqueue while said queue is full.
·           Dequeue: The removal of an item from a queue. Also similar to a stack, an Underflow condition will be ruled if dequeue is used with an empty queue.
·           Front: Returning the front (first) item from a queue.
·           Rear: Returning the last item from a queue.


The Above operators, although also done in a certain order, the order in which a queue is done is FIFO (First in First Out). Example of such a phenomena is, like its name, a real life queue in which the first in line will be served first followed by the second, third, and so on.

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