#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#define NUM 4
 
struct data
{
  char name[20];
  char school[20];
  char city[20];
  char province[20];
}info;
 
struct data addrs[NUM]=
{
  "OKBase","BIT","JiLin","JiLin",
  "TongWei","BIT","ZhengJiang","JiangSu",
  "SunYou","BIT","WeiFang","ShangDong",
  "XiaoMing","PKU","TaiYuan","ShanXi"
 
};
/*對(duì)后面要用到的函數(shù)進(jìn)行聲明*/
void quick_disk(FILE *fp,int count);
void qs_disk(FILE *fp,int left,int right);
void exchangedata(FILE *fp,long i, long j);
char *get_name(FILE *fp, long rec);
void print_data(struct data *p);
struct data *get_data(FILE *fp,long rec);
 
int main(void)
{
  int i;
  FILE *fp;          /*文件指針*/
  /*以讀寫(xiě)方式生成文本文件fp*/
  if((fp = fopen("datalist.txt","w+")) == NULL)
  {
    printf("打開(kāi)文件失敗\n");
    exit(1);
  }
  printf("將未排序的數(shù)據(jù)寫(xiě)入文件\n");
  /*將數(shù)組Sdata[NUM]寫(xiě)入文件中*/
  fwrite(addrs,sizeof(addrs),1,fp);
  /*將文件中的數(shù)組Sdata[NUM]依次取出并打印*/
  for(i=0;i<NUM;i++)
  {
    struct data *p;
    p = get_data(fp,i);   /*得到Sdata[i]的指針*/
    print_data(p);     /*將結(jié)構(gòu)體Sdata[i]各個(gè)成員變量打印出*/
    printf("\n");
  }
 
  fclose(fp);         /*關(guān)閉文件指針*/
  /*以二進(jìn)制方式再次打開(kāi)文件datalist.txt*/
  if((fp=fopen("datalist.txt","rb+"))==NULL)
  {
    printf("不能以讀寫(xiě)方式打開(kāi)文件\n");
    exit(1);
  }
 
  printf("將文件數(shù)據(jù)排序\n");
  /*調(diào)用字符串排序函數(shù)將文本中的字符串結(jié)構(gòu)體排序*/
  quick_disk(fp,NUM);     
 
  printf("排序結(jié)束\n");
  /*將排序結(jié)束后的數(shù)組數(shù)據(jù)打印出來(lái)*/
  for(i=0;i<4;i++)
  {
    struct data *p;
    p = get_data(fp,i);
    print_data(p);
    printf("\n");
  }
  fclose(fp);
 
  return 0;
}
/*應(yīng)用快速排序方法對(duì)字符串進(jìn)行排序*/
void quick_disk(FILE *fp,int count)
{
  qs_disk(fp,0,count-1);
}
/*排序函數(shù)*/
void qs_disk(FILE *fp,int left,int right)
{
  long int i,j;
  char x[30];
  i = left;
  j = right;
  /*比較字符串x為Sdata數(shù)組中間一個(gè)結(jié)構(gòu)變量的name成員變量*/
  strcpy(x,get_name(fp,(long)(i+j)/2));
  do
  {  /*比較當(dāng)前結(jié)構(gòu)變量的name成員變量于比較字符串x的大小*/
    while((strcmp(get_name(fp,i),x)<0)&&(i<right))
      i++;
    while((strcmp(get_name(fp,j),x)>0)&&(j>left))
      j--;
    if(i<=j)
    {
      exchangedata(fp,i,j);    /*交換i和j對(duì)應(yīng)的數(shù)據(jù)*/
      i++;
      j--;
    }
  }while(i<j);
 
  if(left<j)          /*反復(fù)調(diào)用此排序函數(shù)，直到j(luò)達(dá)到數(shù)據(jù)的最左端*/
    qs_disk(fp,left,(int)j);
  if(i<right)         /*反復(fù)調(diào)用此排序函數(shù)，直到i達(dá)到數(shù)據(jù)的最右端*/
    qs_disk(fp,(int)i,right);
}
/*交換i和j在文件中對(duì)應(yīng)的數(shù)據(jù)*/
void exchangedata(FILE *fp,long i,long j)
{
  char a[sizeof(info)],b[sizeof(info)];
  fseek(fp,sizeof(info)*i,SEEK_SET);   /*找到i在文件中對(duì)應(yīng)的數(shù)據(jù)位置*/
  fread(a,sizeof(info),1,fp);       /*將該位置數(shù)據(jù)讀到字符串?dāng)?shù)組a中*/
 
  fseek(fp,sizeof(info)*j,SEEK_SET);   /*找到j(luò)在文件中對(duì)應(yīng)的數(shù)據(jù)位置*/
  fread(b,sizeof(info),1,fp);       /*將該位置數(shù)據(jù)讀到字符串?dāng)?shù)組b中*/
 
  fseek(fp,sizeof(info)*j,SEEK_SET);   /*找到j(luò)在文件中對(duì)應(yīng)的數(shù)據(jù)位置*/
  fwrite(a,sizeof(info),1,fp);      /*將剛才讀入a中的數(shù)據(jù)寫(xiě)入到該位置*/
  fseek(fp,sizeof(info)*i,SEEK_SET);   /*找到i在文件中對(duì)應(yīng)的數(shù)據(jù)位置*/
  fwrite(b,sizeof(info),1,fp);      /*將剛才讀入b中的數(shù)據(jù)寫(xiě)入到該位置*/
  /*完成文件中i和j處對(duì)應(yīng)數(shù)據(jù)的交換*/
}
/*得到文件fp中變量rec對(duì)應(yīng)的結(jié)構(gòu)體變量的name成員變量*/
char *get_name(FILE *fp,long rec)
{
  struct data *p;
  p = &info;
  rewind(fp);
  /*找到該結(jié)構(gòu)體變量得的位置*/
  fseek(fp,rec*sizeof(struct data),SEEK_SET);
  /*將其讀到指針p*/
  fread(p,sizeof(struct data),1L,fp);
  return p->name;     /*返回該結(jié)構(gòu)體變量的name成員變量*/
}
/*得到文件fp中變量rec對(duì)應(yīng)的結(jié)構(gòu)體變量的指針*/
struct data *get_data(FILE *fp,long rec)
{
  struct data *p;
  p = &info;
  rewind(fp);
  /*找到該結(jié)構(gòu)體變量得的位置*/
  fseek(fp,rec*sizeof(info),SEEK_SET);
  /*將其讀到指針p*/
  fread(p,sizeof(info),1,fp);
  return p;        /*返回該結(jié)構(gòu)體指針*/
}
/*將指針p對(duì)應(yīng)的結(jié)構(gòu)體的各個(gè)成員變量打印出來(lái)*/
void print_data(struct data *p)
{
  printf("姓名：%s\n",p->name);
  printf("學(xué)校：%s\n",p->school);
  printf("城市：%s\n",p->city);
  printf("省 ：%s\n",p->province);
}