队列是先入先出的,即先入队的数据先出队
下面程序是队列的顺序存储结构的实现,具有入队,出队,求队列长度的的功能

  1. 程序开头
#include <stdio.h>
#include <stdlib.h>

#define MAXSIZE 100
#define Ok 1
#define ERROR 0

typedef int QElemType;
typedef int Status;

typedef struct {
    QElemType *base;
    int front;
    int rear;
} Squeue;
  1. 程序主题
// 初始化队列
Status InitQueue(Squeue *s) {

    s->base = (QElemType *) malloc(MAXSIZE * sizeof(QElemType));
    if (!s->base) {
        printf("初始化队列失败");
        exit(-1);
    }
    s->front = s->rear = 0;
    return Ok;
}

// 队列的长度
Status GetLen(Squeue s){
    int len;
    len = (s.rear - s.front + MAXSIZE) % MAXSIZE;
    printf("队列的长度为:%d\n",len);
    return Ok;
}

// 插入元素到队列
 Status InsertQueue(Squeue *s, QElemType e){

    if ((s->rear + 1) % MAXSIZE == s->front){
        return ERROR;
    }
    s->base[s->rear] = e;
    s->rear = (s->rear +1 ) % MAXSIZE;

    return Ok;
}

// 输出队列的元素
Status DeQueue(Squeue *s, int *e){
    if (s->front == s->rear) {
        return ERROR;
    }
    *e = s->base[s->front];
    s->front = (s->front + 1) % MAXSIZE;
    return Ok;
}

int main(){
    int n, tmp, num;
    Squeue s;
    InitQueue(&s);
    printf("请输入要入队列元素的个数:");
    scanf("%d",&n);
    for (int i = 0; i < n; i++) {
        printf("请输入第 %d 个值:",i+1);
        scanf("%d",&tmp);
        InsertQueue(&s, tmp);
    }
    GetLen(s);
    for (int j = 0; j < n; j++) {
        DeQueue(&s,&num);
        printf("%d\t",num);

    }
    return 0;
}

代码实现结果:

输入要入队列元素的个数为4,依次输入5,6,89,45,结果输出为5 6 89 45