程序代码：

#include <stdio.h>
#include <stdlib.h>
struct room
{
    int id;/*台桌编号*/
    int suit;/*适合人数*/
    int status;/*台桌状态*/
};
typedef struct room roomstru;




int main()
{
    int number,i=0,k,j=0,l;
    FILE *fp;
    roomstru a[100];
    printf("几人用餐：（1~15）\n");
    scanf("%d",&number);
    if(number<=0||number>=15)
        printf("抱歉，本餐厅不能提供%d人数的服务",number);
    fp=fopen("room.txt","a+");
    printf("座位编号       合适人数      台桌状态(1已订 0空闲）\n");
    while(!feof(fp))
    {    fscanf(fp,"%d%d%d",&a[i].id,&a[i].suit,&a[i].status);
         i++;
    }
    while(number<=a[j].suit)
    {
        j++;
    }
     for(;j<15;j++)
    {printf("%d%14d%14d",a[j].id,a[j].suit,a[j].status);
     printf("\n");
     }
    printf("请输入预订座位编号：\n");
    scanf("%d",&k);
    fprintf(fp,"%d%d%d",a[k-1].id,a[k-1].suit,"1");
    fscanf(fp,"%d%d%d",&a[k-1].id,&a[k-1].suit,&a[k-1].status);
    printf("你已预定%d号桌子，欢迎前往用餐！\n",a[k-1].id);
    fclose(fp);
    return 0;
}