c语言时间戳转日期写入文件

time_t now;
        time(&now);
        // char timestr[16] = {0};
        // long2String(now,timestr);
        time_t PTime = 0;
        // time_t now = 1651075170; // 时间戳，可以用time(&mytime);获取当前时间戳
        struct tm* timeP;
        char buffer[128]= {0};

        /*利用东八区（北京时间,其他国家，美国，英国等，需要相应的进行加或者减X小时），        则真正的换算时间戳为*/

        PTime = now + (8 * 60 *60);
        timeP = localtime(&PTime);    // 转换
        //  printf("%d/%d/%d %d:%d:%d\n",1900+ timeP->tm_year,1+ timeP->tm_mon,

        // timeP->tm_mday, timeP->tm_hour, timeP->tm_min, timeP->tm_sec);
        long2Date(timeP,buffer);

 
        FILE *outFile;
        outFile = fopen("/assets/wy_temp_hum.dat","at+"); 
      
        fwrite(buffer, sizeof(char), strlen(buffer), outFile);
   
        fwrite("\n", 1, 2, outFile);//换行
        fclose(outFile);

//long转字符串
char* long2String( long s1 , char *str);//函数声明 

char* long2String(long s1 , char *str)
{
    sprintf(str, " %4d",s1);
    return str;
 
}
//tm 转日期字符串
char* long2Date( struct tm* timeP , char *str);//函数声明 

char* long2Date(struct tm* timeP , char *str)
{
    sprintf(str,"%d/%d/%d %d:%d:%d  ",1900+ timeP->tm_year,1+ timeP->tm_mon,

     timeP->tm_mday, timeP->tm_hour, timeP->tm_min, timeP->tm_sec);
    return str;
 
}