队列的基本实现代码

//队列的结构定义

typedef int QElemType;

typedef struct
{
QElemType data[MAXSIZE];
int front;
int rear;
}SqQueue;

//初始化一个空队列
Status InitQueue(SqQueue *Q)
{
Q->front = 0;
Q->rear = 0;
return OK;
}

//返回Q的元素个数，也就是队列的当前长度

int QueueLength(Squeue Q)
{
return ((Q.rear - Q.front + MAXSIZE)%MAXSIZE);

}

//若队列未满，则插入元素e为Q新的队尾元素
Status EnQueue (SqQueue *Q,QElemType e)
{
if((Q->rear+1)%MAXSIZE == Q->front)
return ERROR;
Q->data[Q-rear] = e;
Q->rear = (Q-rear+1)%MAXSIZE;

return OK;
}

//若栈不空，则删除Q中对头元素，用e返回其值，并返回OK，否则返回ERROR
Status DeQueue(SqQueue *Q,QElemType *e)
{
if(Q->front == Q-rear)
return ERROR;
*e = Q->data[Q->front];

Q->front = (Q->front+1)%MAXSIZE;

return OK;
}

//队列的链式存储结构

typedef int QElemType;

typedef struct QNode
{
QElemType data;
struct QNode *next;
}QNode,*QueuePtr;

typedef struct
{
QueuePtr front,rear;
}LinkQueue;

//插入元素e为Q新的栈顶元素
Status EnQueue(LinkQueue *Q,QElemType e)
{
QueuePtr s = (QueuePtr)malloc(sizeof(QNode));
if(!s)
exit(OVERFLOW);
s->data = e;
s->next = NULL;
Q->rear->next = s;

Q->rear = s;
return OK;
}

//若栈不空，则删除Q中对头元素，用e返回其值，并返回OK，否则返回ERROR

Status DeQueue(LinkQueue *Q,QElemType *e)
{
QueuePtr p;

if(Q->front == Q->rear)
return ERROR;

p = Q->front->next;
*e = p->data;
Q->front->next = p->next;

if(Q->rear == p)
Q-rear = Q->front;
free(p);

return OK;
}