顺序队列

#include "iostream"
using namespace std;

#define MAXLENGTH 20
typedef struct Queue
{
    int array[MAXLENGTH];
    //first指向将要被删除的元素的下标，tail指向可以被插入元素的位置
    int first,tail;
}Queue;

void initial(Queue *queue)
{
    queue->first = 0;
    queue->tail = 0;
}

//入队
bool enq(Queue *queue,int elem)
{
    //我的想法
//    if (queue->tail == MAXLENGTH-1)
//    {
//        cout<<"overflow!"<<endl;
//        return false;
//    }
    queue->array[queue->tail] = elem;

    if (queue->tail == MAXLENGTH-1)
    {
        queue->tail = 0;
    }
    else
    {
        queue->tail++;
    }

    if (queue->tail == queue->first)
    {
        cout<<"overflow !"<<endl;
        return false;
    }
    return true;
}
//出队
bool deq(Queue *queue)
{
    if (queue->tail == queue->first)
    {
        cout<<"underflow !"<<endl;
        return false;
    }
    else if (queue->first == MAXLENGTH -1)
    {
        queue->first = 0;
    }
    else
    {
        queue->first++;
    }
    return true;
}

void print(Queue queue)
{
    int i = queue.first;
    while (i != queue.tail)
    {
        cout<<queue.array[i]<<endl;;
        i++;
    }
}
//判断队列是否为空
bool isempty(Queue queue)
{
    return queue.first == queue.tail;
}

//读取队首元素
bool readfront(Queue queue,int *elem)
{
    if (isempty(queue))
    {
        return false;
    }
    *elem = queue.array[queue.first];
    return true;
}


int main()
{
    Queue queue;
    initial(&queue);

    enq(&queue,1);
    enq(&queue,2);
    print(queue);
    cout<<"------------------------"<<endl;
    deq(&queue);
    print(queue);

    cout<<"--------------------------"<<endl;
    int elem;
    if(readfront(queue,&elem))
    {
        cout<<elem<<endl;
    }
    return 0;
}