报错use of deleted function ‘std::basic_fstream..的处理

bug1:
在定义print函数的时候,文件输出流没有定义成引用导致以下报错:

use of deleted function ‘std::basic_fstream<_CharT, _Traits>::basic_fstream(const std::basic_fstream<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_traits<char>]’

fix:
void print(Field aField, fstream )改为
void print(Field aField, fstream &)