/*文件名:exam12_13.cpp*/
#include <stdio.h>
#define N 5
typedef struct student
{
	char name[10];
	int score;
} Sttype;
void bubble(Sttype a[]);
main()
{
	FILE *fp;
	Sttype stud[N];
	int i=0;
	if ((fp=fopen("stud.bin","rb"))==NULL) 
	{
		printf("不能讀取stud.bin文件\n");
		return;
	}
	for (i=0;i<N;i++) 
		fread(&stud[i],sizeof(struct student),1,fp);
	bubble(stud);
    fclose(fp);
	if ((fp=fopen("stud.bin","wb"))==NULL) 
	{
		printf("不能建立文件stud.bin\n");
		return;
	}
	for (i=0;i<5;i++)
		fwrite(&stud[i],sizeof(struct student),1,fp);
	fclose(fp);
}
void bubble(Sttype a[])  /*將結構體數組a按score成員遞減排序*/
{
	int i,j,exchange;
	Sttype tmp;
	for (i=0;i<N-1;i++)
	{
		exchange=0;         
		for (j=N-2;j>=i;j--) 
			if (a[j+1].score>a[j].score)
			{
				tmp=a[j+1];
				a[j+1]=a[j];
				a[j]=tmp;
				exchange=1;
			}
            if (!exchange)      /*本趟未發生交換,排序完成,退出for循環*/
                break; 
	}
}