queue.cpp

数据结构课程设计,表达式,用C语言实现,难度系数较高

#include <stdio.h>
#include <stdlib.h>
#include "../header/bitree.h"
#include "../header/queue.h"
#include "../header/stack.h"
#include "../header/expr.h"

Status InitQueue( Queue & Q )
//构造一个空队列
{
	Q.front = Q.rear = ( QuePtr )malloc( sizeof( QNode ) );
	if( !Q.front )
		return FALSE;
	Q.front->next = NULL;
	return OK;
}

Status DestroyQueue( Queue &Q )
//销毁队列
{
	while( Q.front )
	{
		Q.rear = Q.front->next;
		free( Q.front );
		Q.front = Q.rear;
	}
	return OK;
}

Status QueueEmpty( Queue Q )
//判空
{
	return Q.front == Q.rear;
}

Status EnQueue( Queue &Q, QElemType e )
//插入元素e为Q的新的队尾元素
{
	QuePtr p;
	p = ( QuePtr )malloc( sizeof( QNode ) );
	if( !p )
		return FALSE;
	p->data = e;
	p->next = NULL;
	Q.rear->next = p;
	Q.rear = p;
	return OK;
}

Status DeQueue( Queue &Q, QElemType &e )
//删除队头元素，用e返回其值，并返回OK,否则返回ERROR;
{
	if( Q.front == Q.rear )
		return ERROR;
	QuePtr p = Q.front->next;
	e = p->data;
	Q.front->next = p->next;
	if( Q.rear == p )
		Q.rear = Q.front;
	free( p );
	return OK;
}