TheGameCreators - CodeBase - Using an array as a queue

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Category: Core

Version: 1.0

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Uploaded: 15th Sep 2003 14:00

Modified: 15th Sep 2003 14:01

Author: IanM

Summary

Simple readable example of using an array as a queue

Full Description

Simple readable example of using an array as a queue

DarkBASIC Professional Source Code

` This code was downloaded from The Game Creators

` It is reproduced here with full permission

` http://www.thegamecreators.com

` Demonstration of the queue commands

` ADD TO QUEUE       - Adds a new item to the end of the array and

`                       sets the current index to point to that item.

` REMOVE FROM QUEUE  - Removes the first item at the front of the

`                       array sets the current index to point to the

`                       new front item.

` I use ArrayName() to access the current item (eg to set the values

`                       in the item just added to the queue).

` I use ArrayName(0) to access the front of the queue (eg to read the

`                       values prior to removing from the queue)

`                       - see below for the reason.

` Several things to note here:

`   Adding to the queue automatically increases the size of the array.

`   Removing from the queue automatically decreases the size of the

`     array.

`   You cannot create an empty array (at the moment - Lee may include

`     it in Update 6) so the array needs to be cleared before you use

`     it.

`   No example of the 'array index to queue', because there is simply

`     no need for this command (in my opinion).

`     All it does is set the current index to the first item of the

`     array, and you can get that value yourself by accessing array(0).

`     Adding a new item to the queue resets the index to the last item

`     in the array, and continually switching back to get the next

`     value at the front of the queue is a pain.

dim a() as integer

empty array a()

print "Add 5 items to the queue"

for i=1 to 5

n = rnd(1000)

print "  Adding "; n; " to the queue"

add to queue a()

a() = n

next i

PrintQueue()

print "Pop 2 items from the queue"

for i=1 to 2

print "  Removing "; a(0); " from the queue"

remove from queue a()

next i

PrintQueue()

print "Add 5 more entries to the queue"

for i=0 to 4

n = rnd(1000)

print "  Adding "; n; " to the queue"

add to queue a()

a() = n

next i

PrintQueue()

print "Now remove items until the queue is empty"

while array index valid( a() )

print "  Removing "; a(0); " from the queue"

remove from queue a()

endwhile

PrintQueue()

wait key

end

function PrintQueue()

if array count( a() ) >= 0

print "The queue has "; array count( a() )+1; " items"

for i=0 to array count( a() )

print "  Item "; i; " = "; a(i)

next i

else

print "The queue is empty"

endif

endfunction

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Author Name:	IanM
CodeBase Entries:	26

CodeBase - Using an array as a queue

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