# Include <stdio. h>
# Include <stdlib. h>
# Define max_size 50
Typedef struct qnode
{
Int data; // data domain
Struct qnode * Next; // points to the next element
} Qnode, * queueptr; Typedef struct
{
Queueptr front; // queue header pointer
Queueptr rear; // The end pointer of the queue.
Int length; // Queue Length
} Linkqueue; // Construct an empty queue
Void initqueue (linkqueue & Q)
{
Q. Front = Q. Rear = (queueptr) malloc (sizeof (qnode ));
If (! Q. Front)
{
Exit (1 );
}
Q. Front-> next = NULL;
Q. Length = 0;
Return;
} // Destroy the queue
Void destroyqueue (linkqueue & Q)
{
While (Q. Front)
{
Q. Rear = Q. Front-> next;
If (Q. Front)
{
Free (Q. Front );
}
Q. Front = Q. rear;
}
Q. Length = 0;
} // Insert elements into the queue
Void enqueue (linkqueue & Q, int e)
{
If (Q. Length = max_size)
{
Printf ("the queue is full! Element cannot be inserted! ");
}
Else
{
Queueptr P = (queueptr) malloc (sizeof (qnode ));
If (! P)
{
Exit (1 );
}
P-> DATA = E;
P-> next = NULL;
Q. Rear-> next = P; // point to the newly inserted Node
Q. Rear = P;
Q. Length ++; // Add 1 to the number of elements
}
} // Output queue, from the queue Header
Void dequeue (linkqueue * q, int e)
{
// The queue cannot be deleted because it is empty.
If (Q-> front = Q-> rear)
{
Printf ("the queue is empty and cannot be deleted! ");
} Else
{
Queueptr P = Q-> front-> next; // retrieve the queue Header
E = p-> data;
Q-> front-> next = p-> next; // delete node P
Q-> length --; // The number of elements minus 1
// If the queue has only one element
If (Q-> rear = P)
{
Q-> rear = Q-> front;
}
If (P! = NULL)
{
Free (P );
P = NULL;
}
}
} // Calculate the queue length
Int getlength (linkqueue * q)
{
Return Q-> length;
} // Retrieve the queue Header element
Int gethead (linkqueue * q)
{
If (0 = Q-> length)
{
Printf ("the queue is empty! \ N ");
}
Else
{
Return Q-> front-> next-> data;
}
} // Obtain the end element of the queue
Int gettail (linkqueue * q)
{
If (0 = Q-> length)
{
Printf ("the queue is empty! \ N ");
}
Else
{
Return Q-> rear-> data;
}
}
Void main ()
{
Linkqueue Q;
Initqueue (Q );
Enqueue (Q, 1 );
Enqueue (Q, 2 );
Enqueue (Q, 3 );
// Dequeue (& Q, 0 ); Int Len = getlength (& Q );
Printf ("the queue has several elements in total: % d, % d, % d \ n", Len, gethead (& Q), gettail (& Q ));
Int daxiao = sizeof (qnode );
} |
