#include <fstream>
istream& read( char* buffer, streamsize num );

ifstream fin( "/tmp/data.txt" );
ofstream fout( "/tmp/results.txt", ios::app );
while( fin >> temp )
fout << temp + 2 << endl;
fin.close();
fout.close();

先用int fd=open(“filepath”)打開文件；獲得文件描述符
然后read（fd,buf,sizeof(buf)）;