线性队列

队列是先进先出，和栈相反.

不循环的队列就是浪费空间，如果tail到了最大值后，即使前面出队了，有空的位置，也不能再入队。

seqqueue.h

#ifndef __SEQQUEUE__
#define __SEQQUEUE__

#include <stdio.h>
#include <malloc.h>
#include <assert.h>
#include <memory.h>
#include <stdbool.h>

#define SEQQUEUE_INIT_SIZE 8

typedef int ElemType;

typedef struct seqqueue{
  ElemType* base;
  int front;
  int tail;
}seqqueue;

void init(seqqueue*);
void enQueue(seqqueue*, ElemType);
void show_list(seqqueue*);
void deQueue(seqqueue*);
void clear(seqqueue*);
void destroy(seqqueue*);
#endif

seqqueue.c

#include "seqqueue.h"

void init(seqqueue* seq){
  seq->base = (ElemType*)malloc(sizeof(ElemType) * SEQQUEUE_INIT_SIZE);
  seq->front = seq->tail = 0;
}
void enQueue(seqqueue* seq, ElemType x){
  if(seq->tail == SEQQUEUE_INIT_SIZE -1){
    printf("queue is full\n");
    return;
  }
  seq->base[seq->tail++] = x;
}
void show_list(seqqueue* seq){
  int i = seq->front;
  while(i <= seq->tail-1){
    printf("%d\n", seq->base[i++]);
  }
}
void deQueue(seqqueue* seq){
  if(seq->front < SEQQUEUE_INIT_SIZE - 1){
    seq->front++;
  }
}
void clear(seqqueue* seq){

}
void destroy(seqqueue* seq){

}

whilequeuemain.c

#include "seqqueue.h"

int main(){
  seqqueue list;
  init(&list);
  int select = 1;
  ElemType item;
  int index;
  while(select){
    printf("*****************************************\n");
    printf("*** [1]   push        [2]  pop        ***\n");
    printf("*** [3]   show_list   [4]  length     ***\n");
    printf("*** [5]   clear       [6]  destroy    ***\n");
    printf("*** [0]   quit                        ***\n");
    printf("*****************************************\n");
    printf("请选择:>");
    scanf("%d", &select);
    if(0 == select)
      break;
    switch(select){
    case 1:
      printf("请输入要插入的数据>\n");
      scanf("%d",&item);
      enQueue(&list, item);
      show_list(&list);
      break;
    case 2:
      deQueue(&list);
      show_list(&list);
      break;
    case 3:
      show_list(&list);
      break;
    case 5:
      clear(&list);
      show_list(&list);
      break;
    case 6:
      destroy(&list);
      break;
    default:
      printf("输入的选择错误，请重新选择\n");
      break;
    }
  }
  //destroy(&list);                                                             
}