| As I said earlier, every time we delete an element from
the queue, the "front" value increments by 1 till the time it
reaches the upper limit of queue; after which it starts all over again
from 0. Here, we'll be checking the "Queue empty" condition;
and if the queue is empty then we'll flash an error message or else
we'll delete that front element.
The queue is supposed to be Empty when it
contains a NULL value for its "front" element. Fine!
Algorithm for deletion:-
Step-1:
If the queue is empty then say "empty queue" and quit; else
continue
Step-2: Delete the "front" element
Step-3: If the "front" is pointing to the last position
of the queue then step-4 else step-5
Step-4: Make the "front" point to the first position in
the queue and quit
Step-5: Increment the "front" position by one
C implementation:-
int max; /*the
maximum limit has already been set*/
static int queue[max];
int front=0, rear=-1; /*queue
is initially empty*/
..
..
main( )
{
..
..
addval(23);
..
del_value = delval( );
..
addval(47);
..
}
int delval( )
{
int deleted_front = 0;
if (front == NULL) /*step-1*/
printf("Queue empty");
else
{
deleted_front = queue[front];
queue[front] =
NULL; /*step-2*/
if (front ==
max-1) /*step-3*/
front =
0; /*step-4*/
else
front = front +
1;/*step-5*/
}
return(deleted_front);
}
Related Operations:
Queues
- Concepts
Array implementation - add( ) and delete(
)
Linked List implementation - add( )
and delete( )
Circular queues - add( ) and delete(
)
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