C语言开发之循环队列的实现

c语言开发之循环队列的实现：c语言开发之循环队列的又该怎么实现呢？有什么方法呢？希望下面的文章对大家有所帮助。

运行环境：vs2015

#include
#include
#include 
//-------定义-----
typedef int elemtype;
typedef int status;
//------定义常量的值
#define ok 1
#define error 0
#define true 1
#define false 0
#define overflow 0
//----------结构体-----------
typedef struct {
    elemtype *elem;  //存储空间基址
    int front;      //队头位标
    int rear;       //队尾位标，指示队尾元素的下一个位置
    int maxsize;        //存储容量
}sqqueue;

//---------------接口声明--------
status initqueue_sq(sqqueue &q, int size);  //构造一个新队列
status destoryqueue_sq(sqqueue &q);         //销毁队列q，q不再存在
void clearqueue_sq(sqqueue &q);     //将q置为空队列
status queueempty_sq(sqqueue q);        //判断队列是否为空
int queuelength_sq(sqqueue q);      //返回队列q中的元素个数，即队列的长度
status gethead_sq(sqqueue q, elemtype e);   //若队列不空，则用e返回q的队列头元素
status enqueue_sq(sqqueue &q, elemtype e);//在队尾之后插入元素e，为新的队尾元素
status dequeue_sq(sqqueue &q, elemtype &e);     //出队

//----------初始化循环队列------
status initqueue_sq(sqqueue &q, int size) {
    q.elem = (elemtype *)malloc(size * sizeof(elemtype));  //分配空间
    if (q.elem == null) return overflow;    //分配空间失败
    q.front = q.rear = 0;       //置队列为空队列
    q.maxsize = size;   //赋值，设定存储空间长度
    return ok;
}

//----------销毁循环队列---------
status destoryqueue_sq(sqqueue &q) {
    q.front = q.rear = 0;       //置队为空
    q.elem = null;      //把基址设为null
    q.maxsize = 0;
    free(q.elem);
    return ok;
}

//------清空循环队列------
void clearqueue_sq(sqqueue &q) {
    q.front = q.rear = 0;
}

//------判断循环队列是否为空------
status queueempty_sq(sqqueue q) {
    if (q.front == q.rear)
        return true;
    else return false;
}

//------计算队列长度-----
int queuelength_sq(sqqueue q) {
    if (q.rear >= q.front) {        //考虑两个都是0的情况
        return (q.rear-q.front);        
    }else {
        return (q.rear - q.front + q.maxsize + 1);  //q.rear-q.front+q.maxsize+1
    }
}

//----若队列不空，则用e返回q的队列头元素---
status gethead_sq(sqqueue q, elemtype e) {
    if (queueempty_sq(q) == false) {        //注意细节!
        e = q.elem[q.front];
        return e;
    }
    else {
        return error;
    }
}

//---在队尾之后插入元素e，为新的队尾元素---
status enqueue_sq(sqqueue &q, elemtype e) {
    if (q.front == (q.rear + 1) % (q.maxsize)) {    //队满条件  少用一个元素空间
        return overflow;
    }
    else {
        q.elem[q.rear] = e;
        q.rear = (q.rear + 1) % q.maxsize;  //q.rear循环+1
        return e;
    }
}

//----出队---
status dequeue_sq(sqqueue &q, elemtype &e) {
    if (q.front == q.rear)      //队空
        return error;
    e = q.elem[q.front];
    q.front = (q.front + 1) % q.maxsize;    //队头循环+1
    return e;
}

void main() {
    sqqueue q;
    elemtype e = 0;
    int length1;
    //构造新队列
    initqueue_sq(q, 8);
    //入队
    for (int i = 0; i < 12; i++) {
        enqueue_sq(q, i+1);
    }
    length1 = queuelength_sq(q);
    //遍历循环队列
    for (int i = 0; i < length1; i++) {
        printf("%d\n", q.elem[i]);
    }
    //出队操作
    printf("执行出队操作,出队3个元素：\n");
    for (int i = 0; i < 3; i++) {
        dequeue_sq(q, e);
    }
    length1 = queuelength_sq(q);
    for (int i = q.front; i < q.rear; i++) {
        printf("%d\n", q.elem[i]);
    }
    printf("执行入队操作,入队2个元素：\n");
    for (int i = 0; i < 2; i++) {
        enqueue_sq(q, i + 1);
    }
    for (int i = q.front; i < q.maxsize; i++) {
        printf("%d\n", q.elem[i]);
    }
    for (int i = 0; i < q.rear; i++) {
        printf("%d\n", q.elem[i]);
    }
    printf("返回队头元素为:%d\n", gethead_sq(q, e));
}