队列

#include <stdio.h>

#define QUEUE_SIZE  100
#define OK            0   
#define ERROR        -1    

typedef int DataType;
typedef struct
{
	DataType data[QUEUE_SIZE];
	int rear, front;
}SeqQueue;

// 置空队列
int InitQueue(SeqQueue *q)
{
	if (q == NULL)
	{
		return ERROR;
	}
	
	q->rear = 0;
	q->front = 0;
	
	return OK;
}

// 判断是否空队
int QueueEmpty(SeqQueue *q)
{
	if (q == NULL)
	{
		return ERROR;
	}
	
	return q->rear == q->front;
}

// 判断是否队满
int QueueFull(SeqQueue *q)
{
	if (q == NULL)
	{
		return ERROR;
	}
	
	return (q->rear+1)%QUEUE_SIZE == q->front;
}

// 入队
int EnQueue(SeqQueue *q, int data)
{
	if (q == NULL)
	{
		return ERROR;
	}
	
	if (QueueFull(q))
	{
		return ERROR;
	}
	
	q->rear = (q->rear+1) % QUEUE_SIZE;
	q->data[q->rear] = data;
	
	return OK;
}

// 出队
int DeQueue(SeqQueue *q)
{
	if (q == NULL)
	{
		return ERROR;
	}
	
	if (QueueEmpty(q))
	{
		return ERROR;
	}
	
	q->front = (q->front+1) % QUEUE_SIZE;
	
	return q->data[q->front];
}

// 获取队头元素
int GetFront(SeqQueue *q)
{
	if (q == NULL)
	{
		return ERROR;
	}
	
	if (QueueEmpty(q))
	{
		return ERROR;
	}
	
	int pos = (q->front+1) % QUEUE_SIZE;
	
	return q->data[pos];
	
}


int main()
{
	SeqQueue queue;
	if (InitQueue(&queue) != OK)
	{
		return -1;
	}
	
	if (QueueEmpty(&queue))
	{
		printf ("空队列\n");
	}
	else
	{
		printf ("不是空队列\n");
	}
	
	int i=0;
	for (i = 0; i<10; i++)
	{
		EnQueue(&queue, i);
	}
	
	if (QueueEmpty(&queue))
	{
		printf ("空队列\n");
	}
	else
	{
		printf ("不是空队列\n");
	}
	
	for (i = 0; i<10; i++)
	{
		printf ("%4d", DeQueue(&queue));
	}
	
	
	if (QueueEmpty(&queue))
	{
		printf ("空队列\n");
	}
	else
	{
		printf ("不是空队列\n");
	}
	
    return 0;
}