下面是停车场管理系统的代码。
看到的朋友们给点意见，还有就是在文件方面的应用。  谢谢。。
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
FILE*fp;
char infile[]="stop.txt";
struct station{
    char carname[90];
    time_t stoptime;
    int sky;
}sta[50];
int num=0;
void spare ();//查空车位
void stop ();//停车
void live ();//离开
void fprintf ();
void face ();
void spare ()
{
    fp=fopen ("stop.txt","r");
    int i;
    if (num>=50)
    {
        printf ("对不起，停车场已满！");
    }
    else
    {
        printf ("以下位置是空的：\n\n");
        for(i=0;i<50;i++)
        {
            if (sta[i].sky ==0)
            {
                printf ("%d号\t",i+1);
            }
        }
    }
}
void stop ()
{
    for (int i=0;i<50;i++)
    {
        if (sta[i].sky==0)
        {
            fp=fopen ("stop.txt","a+");
            printf ("请输入您的车牌号：");
            scanf ("%s",sta[num].carname);
            fputs (sta[num].carname,fp);
            sta[num].stoptime=time(NULL);
            
            printf ("您的停车时间是：");
            printf ("%s",ctime(&sta[num].stoptime));
            printf ("您好！已经完成操作！");
            sta[num].sky = num+1;
            num++;
            fclose (fp);
            break;
        }
    }
}
void live ()
{
    fp=fopen ("stop.txt","r");
    int i;
    time_t ts;
    char carname[90];
    long money;
    printf ("请输入您的车牌号：");
    scanf ("%s",carname);
    for (i=0;i<=50;i++)
    {
        if (strcmp(sta[i].carname,carname)==0)
        {
            ts=time(NULL);
            sta[i].sky=0;
            money=ts-sta[i].stoptime;
            printf ("您的开车时间是：");
            printf ("%s\n",ctime(&ts));
            printf ("%ld\n",money);
            if (money/60>=30&&money<60)
            {
                printf ("您应交3元！祝您一路平安！");
            }
            else if (money/60>=60&&money/60<120)
            {
                printf ("您应交5元！祝您一路平安！");
            }
            else if (money/60>=120&&money<180)
            {
                printf ("您应交10元！祝您一路平安！");
            }
            else if (money/60<30)
            {
                printf ("您应交0元！祝您一路平安！");
            }
            else
            {
                printf ("您应交20元！祝您一路平安！");
            }
        }
    }
}
void fprintf ()
{
    fp=fopen ("stop.txt","r");
    printf ("车牌号\t\t\t\t停车时间\n");
    for (int i=0;i<=num;i++)
    {
        if (sta[i].sky!=0)
        {
            printf ("%s\t\t\t",sta[i].carname);
            printf ("%s",ctime(&sta[i].stoptime));
        }
    }
}
void face ()
{
    int choose;
    printf ("\n\n\n\n\n\n\n\t\t\t\t++++++++++++++++++\n");
    printf ("\t\t\t\t||0.        退出||\n");
    printf ("\t\t\t\t||1.        停车||\n");
    printf ("\t\t\t\t||2.        取车||\n ");
    printf ("\t\t\t\t||3.显示所有数据||\n");
    printf ("\t\t\t\t++++++++++++++++++\n");
    scanf ("%d",&choose);
    switch (choose)
    {
    case 3:
        {
            system ("cls");
            fprintf ();
            system("pause");
            system ("cls");
            face ();
            break;
        }
    case 1:
        {
            system ("cls");
            spare ();
            stop ();
            system("pause");
            system ("cls");
            face ();
            break;
        }
    case 2:
        {
            system ("cls");
            live ();
            system("pause");
            system ("cls");
            face ();
            break;
        }
    case 0:
        break;
    }
}
void main ()
{
    printf ("\n\n\n\n\t\t\t     欢迎进入停车场管理系统\n\n");
    printf ("\n********************************************************************************\n\n\n\n\t\t\t        ");
    system("pause");
    system ("cls");
    for (int i=0;i<50;i++)
        sta[i].sky = 0;
    face ();
}

本来要用文件来存储的。  可是对于文件，我是真的有点搞不懂。