void writeReslut2(char* caseName,double averageTime,double max, double min,int loops,int size){    fpos_t pos = 0;    fpos_t endpos = 0;    FILE *fp = fopen("E:\\PerformanceResult.txt","at");    if(NULL == fp){        printf("open file failed !\n");        return ;    }    //printf("%d\n",ftell(fp));    fgetpos(fp,&pos);    //printf("pos = %d\n",pos);    fseek(fp,0L,SEEK_END);    fgetpos(fp,&endpos);    //printf("endpos=%d\n",endpos);    if(pos == endpos){
   //文件为空，写入标题:方法名 平均时间 最大值 最小值 循环次数 读写大小        fprintf(fp,"%-30s %-20s %-20s %-20s %-10s %-10s\n","caseName","averageTime(ms)","maxTime(ms)","minTime(ms)","loops","size(KB)");    }    fseek(fp,0L,SEEK_END);    fprintf(fp,"%-30s %-20f %-20f %-20f %-10d %-10d\n",caseName,averageTime,max,min,loops,size);    fclose(fp);}

通过文件打开的指正位置，以及结尾的指正位置判断