/* 按測驗成績循序排序*/
#include "stdio.h"
void SortByScore()
 {
    int i,j,k;
    student TmpS;   /*定義進行操作時的臨時結構體變量*/
    student s[SIZE];/*SIZE，在score.h頭文件中定義的常量，值為5  */
    int recNumber = 0;
    char DataFile[40] = "record"; /*DataFile存儲排行榜信息的文件名*/
    FILE *fp;/*fp指針指向存儲數據的文件名*/
    /*以讀的方式打開文件，如文件不存在，提示錯誤*/
    fp=fopen(DataFile,"rb");
    if (fp == NULL)
    {
        printf("\nOpen file %s fail!End with any key\n",DataFile);
        perror("Open file fail");
        getch();
        exit(1);
    }
   /*將文件中要排序的信息存入結構體數組*/
    while((fread(&TmpS,sizeof(student),1,fp)) != (int)NULL)
    {
        strcpy(s[recNumber].name, TmpS.name);
        s[recNumber].score=TmpS.score;
        recNumber++;
    }
    fclose(fp);
 /*====如果文件中有記錄，則將各條記錄按測驗成績值排序===*/
    if(recNumber>1)
    {
        /*====用選擇排序法進行按測驗成績的排序====*/
        for(i=0;i<recNumber-1;i++)
        {
            k = i;
            for(j=i+1;j<recNumber;j++)
            {
                if(s[k].score<s[j].score) k = j;
            }
            strcpy(TmpS.name,s[k].name);
            TmpS.score = s[k].score;


            strcpy(s[k].name,s[i].name);
            s[k].score = s[i].score;

            strcpy(s[i].name,TmpS.name);
            s[i].score = TmpS.score;
        }

        /*將排序好的結構體記錄寫入排行榜文件*/
        fp=fopen(DataFile,"wb+");
        if (fp == NULL)
        {
            printf("\nSet up file %sfail !end with anykey.\n",DataFile);
            perror("Set up fail");
            getch();
            exit(1);
        }
        for(i=0; i<recNumber; i++)
        {
            if(fwrite(&s[i],sizeof(student),1,fp)!=1)
            {
                printf("\nWrite file %s fail!end with anykey.\n",DataFile);
                perror("Write file fail!");
                    getch();
                    exit(1);
            }
        }
        fclose(fp);
    }
     /*顯示排序后的排行榜文件*/
    printf("the student's score in file %s is as flow:.\n",DataFile);

    fp=fopen(DataFile,"rb");
    if (fp == NULL)
    {
        printf("\nOpen file%sfail!End with any key \n",DataFile);
        perror("Open file fail");
        getch();
        exit(1);
    }

    printf("\nname\tscore\n");
    while(fread(&TmpS,sizeof(student),1,fp) != (int)NULL)
    {
        printf("\n%s\t%d\n",TmpS.name,TmpS.score);
    }
    fclose(fp);
    getch();
}