Queue array and linked list implementation

1. the queue is the first-in-first-out data structure, which can be implemented using arrays or linked lists. When using an array to implement a linked list, you need to pre-allocate the size of the array. The front and rear subscripts are used to indicate the subscript of the element at the head and end of the team respectively. When inserting an element, add 1 to the subscript rear at the end of the team. When an element is deleted, add 1 to the front subscript to determine whether the queue is empty, as long as the front and rear are equal. The queue insertion operation can be expressed

# include 
 
  # include 
  
   # define Maxsize  100struct queue {int front;int rear;int q[Maxsize];};int main(){   void initialqueue(queue*);void push(queue *,int);int pop(queue*);int isempty(queue*);int isfull(queue*);queue p;initialqueue(&p);push(&p,1);push(&p,2);push(&p,3);    printf("%d\n",isempty(&p));printf("%d\n",pop(&p));system("pause");return 0;}void initialqueue(queue *p){p->front=p->rear=0;}int isfull(queue *p){return p->rear==p->front+Maxsize-1;}int isempty(queue *p){return p->front==p->rear;}void push(queue* p,int x){if(isfull(p)){printf("queue is full\n");exit(-1);}p->q[p->rear++]=x;}int pop(queue *p){if(isempty(p)){printf("queue is empty\n");exit(-1);}return p->q[p->front++];}
  
 

2. Implement queue through linked list

To implement a queue using a linked list, you need to define the value and pointer of the node struct storage node. In addition, you also need to define the header pointer and tail pointer, pointing to the head and end of the team respectively. The insert element operation can be expressed

# include 
 
  # include 
  
   struct node{int num;node *next;};typedef struct {node *front;node *rear;}link;int main(){void initialqueue(link p);link push(link,int);int pop(link);int isempty(link);int isfull(link);link p={0,0};initialqueue(p);p=push(p,1);p=push(p,2);p=push(p,3);printf("%d\n",pop(p));system("pause");return 0;}void initialqueue(link p){p.front=p.rear=0;}int isempty(link p){return p.front==NULL&&p.rear==NULL;}link push(link p,int x){node *t=(node *)malloc(sizeof(node));t->num=x;t->next=NULL;if(isempty(p)){p.front=p.rear=t;}else{p.rear->next=t;p.rear=t;}return p;}int pop(link p){int temp;node *t;if(isempty(p)){printf("queue is empty\n");exit(-1);}if(p.front!=p.rear){temp=p.front->num;t=p.front;p.front=p.front->next;free(t);}else{temp=p.front->num;t=p.front;p.front=p.rear=NULL;free(t);}return temp;}