Write a C program to implement a queue of at most elements using an array of size n.⦁ At the beginning of your code (outside all subprograms), declare a datatype named `struct Queue`. It must be designed according to the pseudo codes (refer to Figure 2) and the provided main function⦁ Define the subprograms to implement the build, enqueue, and dequeue operations. The meaning of enqueue and dequeue is explained in the pseudocodes in Figure 2. The pseudocodes do not include error checking for underflow and overflow. You are required to extend and implement them to prevent underflow and overflow of the queue. ⦁ Additionally, your code must check for any other potential errors, such as accessing null pointers. Also, add a few comments to your code to explain the behavior of the main and subprograms. Ensure that your build, enqueue, and dequeue operations print informative messages as demonstrated in Figure 3. Ensure you test your code with varying sequences of enqueue and dequeue operations. Including five test cases should be sufficient APIvoid build(struct Queue **q, unsigned int length)void enqueue(struct Queue *q, char x)char dequeue(struct Queue *q)(a) QReturn valueBuilds the queue of the specified length'. Initializesthe queue elements. The memory address of thecreated queue is stored in q.No return value. Side effect; x stored at the tail ofQ. The tail is incremented by one.1(b) Q35Returns the value stored at the head. Headincremented. Returns error code, if someencountered.1 2 3 4 5 6 7 8 915 69Q.head = 72 3 4 5 6 7 8 910 11 1284Q.tail 3 Q.head = 7Q.tail = 1210 11 1215 69 84 1712 3 4 5 6 7 8 9 10 11 12(c) Q3515 698 4 17Q.tail = 3Q.head=8Figure 1 A queue implemented using an array Q[1..12].Figure 1 shows the effects of the enqueue and dequeue operations. Queue elementsappear only in the lightly shaded positions. Figure 1(a) shows a case where the queuehas 5 elements, in locations Q[7..11]. Figure 1(b) shows the configuration of the queueafter the calls ENQUEUE(Q.17), ENQUEUE(Q, 3), and ENQUEUE(Q, 5). Figure1(c) shows the configuration of the queue after the call DEQUEUE(Q) which returnsthe key value 15 formerly at the head of the queue. The new head has the value 6(stored at the position 8).The following pseudo codes describe the meaning of the enqueue and dequeueoperations. ENQUEUE (Q, x)Q[Q.tail] = Xif Q.tail == Q.lengthQ.tail 1=else Q.tail = Q.tail + 11234DEQUEUE(Q)1 x23x = Q[Q.head]if Q.head == Q.lengthQ.head = 145 return xFigure 2 Pseudocodes for enqueue and dequeue subprogramselse Q.head =enqueue(qptr, 1);enqueue(qptr, 2);enqueue(qptr, 3);enqueue(qptr, 4);enqueue(qptr, 5);enqueue(qptr, 6);build(&qptr, 5);//====== Beginn Test CaseTestYour code will be tested using the following main function:int main(int argc, const char * argv[]) {struct Queue *qptr = NULL;Q. head + 1printf("Dequeue() %d\n", dequeue(qptr));printf("Dequeue() %d\n", dequeue(qptr));printf("Dequeue() %d\n", dequeue(qptr));printf("Dequeue() %d\n", dequeue(qptr));printf("Dequeue() %d\n", dequeue(qptr));printf("Dequeue() %d\n", dequeue(qptr));//====== End Test Case// free anything that was created with mallocif (qptr->data) free(qptr->data);if(qptr) free(qptr);

Define the Queue Structure:Define a structure named struct Queue to hold the queue's information.The…

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ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

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Section: Chapter Questions

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Question

Write a C program to implement a queue of at most elements using an array of size n.

⦁ At the beginning of your code (outside all subprograms), declare a datatype named `struct Queue`. It must be designed according to the pseudo codes (refer to Figure 2) and the provided main function
⦁ Define the subprograms to implement the build, enqueue, and dequeue operations. The meaning of enqueue and dequeue is explained in the pseudocodes in Figure 2. The pseudocodes do not include error checking for underflow and overflow. You are required to extend and implement them to prevent underflow and overflow of the queue.

⦁ Additionally, your code must check for any other potential errors, such as accessing null pointers. Also, add a few comments to your code to explain the behavior of the main and subprograms. Ensure that your build, enqueue, and dequeue operations print informative messages as demonstrated in Figure 3.

Ensure you test your code with varying sequences of enqueue and dequeue operations. Including five test cases should be sufficient

API
void build(struct Queue **q, unsigned int length)
void enqueue(struct Queue *q, char x)
char dequeue(struct Queue *q)
(a) Q
Return value
Builds the queue of the specified length'. Initializes
the queue elements. The memory address of the
created queue is stored in q.
No return value. Side effect; x stored at the tail of
Q. The tail is incremented by one.
1
(b) Q35
Returns the value stored at the head. Head
incremented. Returns error code, if some
encountered.
1 2 3 4 5 6 7 8 9
15 69
Q.head = 7
2 3 4 5 6 7 8 9
10 11 12
84
Q.tail 3 Q.head = 7
Q.tail = 12
10 11 12
15 69 84 17
1
2 3 4 5 6 7 8 9 10 11 12
(c) Q35
15 698 4 17
Q.tail = 3
Q.head=8
Figure 1 A queue implemented using an array Q[1..12].
Figure 1 shows the effects of the enqueue and dequeue operations. Queue elements
appear only in the lightly shaded positions. Figure 1(a) shows a case where the queue
has 5 elements, in locations Q[7..11]. Figure 1(b) shows the configuration of the queue
after the calls ENQUEUE(Q.17), ENQUEUE(Q, 3), and ENQUEUE(Q, 5). Figure
1(c) shows the configuration of the queue after the call DEQUEUE(Q) which returns
the key value 15 formerly at the head of the queue. The new head has the value 6
(stored at the position 8).
The following pseudo codes describe the meaning of the enqueue and dequeue
operations.

ENQUEUE (Q, x)
Q[Q.tail] = X
if Q.tail == Q.length
Q.tail 1
=
else Q.tail = Q.tail + 1
1
2
3
4
DEQUEUE(Q)
1 x
2
3
x = Q[Q.head]
if Q.head == Q.length
Q.head = 1
4
5 return x
Figure 2 Pseudocodes for enqueue and dequeue subprograms
else Q.head =
enqueue(qptr, 1);
enqueue(qptr, 2);
enqueue(qptr, 3);
enqueue(qptr, 4);
enqueue(qptr, 5);
enqueue(qptr, 6);
build(&qptr, 5);
//====== Beginn Test Case
Test
Your code will be tested using the following main function:
int main(int argc, const char * argv[]) {
struct Queue *qptr = NULL;
Q. head + 1
printf("Dequeue() %d\n", dequeue(qptr));
printf("Dequeue() %d\n", dequeue(qptr));
printf("Dequeue() %d\n", dequeue(qptr));
printf("Dequeue() %d\n", dequeue(qptr));
printf("Dequeue() %d\n", dequeue(qptr));
printf("Dequeue() %d\n", dequeue(qptr));
//====== End Test Case
// free anything that was created with malloc
if (qptr->data) free(qptr->data);
if(qptr) free(qptr);

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