stack vs queuing?

Question

hello im still a student and im a bit confused about stacking and queuing ? first question is,

1. what is the main diffrence between them two ?

2. btw there is circular queuing beside normal queuing how about that ? how do they work ? is there any different ways to queuing?

3. im useing php, is there a simple ( very simple or easy to read ) sample code that i can learn on ( links are okay too. )?

4. there is pop, push and etc ( stacking and queuing ), is there anything like that in php ?

Thank you very much for looking in.

Answer 1

1: While with stacks the insert/removal operations both work on the same end of the data structure (top)

with queues the insertion takes place at one end (rear) and the removal at the other end (front).

(Both images are from the respective wikipedia entries)

2: see http://en.wikipedia.org/wiki/Circular_buffer

3: and 4: see SplStack and SplQueue

Answer 2

In php you would use an array() to hold your data for both stacks and queues and use the array_* functions to manipulate them. Take a look at array functions at php.net

You have

• array_push - put a new element at end of array
• array_pop - remove an element from end of array
• array_shift - remove an element from the beginning of array

• array_unshift - put a new element onto the beginning of array.

• For a stack you'd use array_push and array_pop

• For a queue you'd use array_push and array_shift

A circular buffer I would implement as a standalone object.