Queues
Queues
Queues
“A Queue is a special kind of list, where items
are inserted at one end
(
the rea
r
)
And deleted
(
)
at the other end (the front)”
Other Name:
First In First Out (FIFO)
First
In
First
Out
(FIFO)
Common O
p
erations on
Q
ueues
pQ
(Queue ADT)
1. ISNULL(): Return true if Queue is Full.
2. FRONT(
)
:Returns the first element on
Q
ueue.
)
Q
3. ENQUEUE(Q): Inserts element Q at the end.
4
DEQUEUE():
Deletes the first element
4
.
DEQUEUE():
Deletes
the
first
element
.
5. EMPTY(): Returns true if and only if Queue is
t
emp
t
y.
Example:
Example:
Line of customers in a bank
Aliti fQ
A
pp
li
ca
ti
ons o
f
Q
ueues
•
Operating system
•
Operating
system
– multi-user/multitasking environments, where
several users or task may be requesting the same
several
users
or
task
may
be
requesting
the
same
resource simultaneously.
•
Comm nication Soft are
•
Comm
u
nication
Soft
w
are
– queues to hold information received over networks
ddi l ti (I f ti b
an
d
di
a
l
up connec
ti
ons.
(I
n
f
orma
ti
on can
b
e
transmitted faster than it can be processed, so is
placed in a queue waiting to be processed)
placed
in
a
queue
waiting
to
be
processed)
• Some other?
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