队列

队列：也是一个线性表（即包括顺序队列和链式队列），先进先出，但限制在两端进行插入和删除

　　　队尾：进行存入操作的一端

　　　队头：进行删除操作的一端

顺序队列：

//sqqueue.h
#ifndef _SQ_QUEUE_H_H
#define _SQ_QUEUE_H_H

#define N 6

typedef int data_t;
typedef struct{
    data_t data[N];
    int front;//指向头
    int rear;//指向尾的后一个    
}sqqueue;

sqqueue *sqqueue_create();
int sqqueue_free(sqqueue *q);
int sqqueue_in(sqqueue *q, data_t value);
data_t sqqueue_out(sqqueue *q);
int sqqueue_empty(sqqueue *q);
int sqqueue_full(sqqueue *q);
int sqqueue_clear(sqqueue *q);
void sqqueue_show(sqqueue *q);


#endif

//sqqueue.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "sqqueue.h"

sqqueue *sqqueue_create()
{
    sqqueue *q = (sqqueue *)malloc(sizeof(sqqueue));
    if(q == NULL){
        printf("malloc failed!\n");
        return NULL;
    }
    memset(q->data, 0, sizeof(q->data));
    
    q->front = 0;
    q->rear = 0;
    
    return q;
}
int sqqueue_free(sqqueue *q)
{
    if(q == NULL){
        printf("queue is NULL\n");
        return -1;
    }
    free(q);
}

/*
*ret @ 1-empty
*/
int sqqueue_empty(sqqueue *q)
{
    if(q->front == q->rear){
        return 1;
    }else{
        return 0;
    }
}
/*
*ret @ 1-full
*/
int sqqueue_full(sqqueue *q)
{
    if((q->rear+1)%N == q->front){
        return 1;
    }else{
        return 0;
    }        
}

int sqqueue_in(sqqueue *q, data_t value)
{
    if(sqqueue_full(q)){
        printf("queue is full,not in\n");
        return -1;
    }
    q->data[q->rear] = value;
    q->rear = (q->rear+1)%N;

    printf("\n");
    return 0;
}
data_t sqqueue_out(sqqueue *q)
{
    if(sqqueue_empty(q)){
        printf("queue is empty,not out\n");
        return -1;
    }
    data_t data = q->data[q->front];
    q->front = (q->front+1)%N;
    return data;
}

int sqqueue_clear(sqqueue *q)
{
    return 0;
}
void sqqueue_show(sqqueue *q)
{
    while(!sqqueue_empty(q)){
        printf("%d\t",sqqueue_out(q));
    }
    printf("\n");    
}

//sqqueue_test.c
#include <stdio.h>
#include "sqqueue.h"

int main()
{
    sqqueue *q = sqqueue_create();
    sqqueue_in(q, 10);
    sqqueue_in(q, 20);
    sqqueue_in(q, 30);

    

    sqqueue_show(q);
    sqqueue_free(q);
    return 0;
}