修改成size_t 还是报错
G:\CODE\homework\classtest\newBookStorage.cpp(35) : error C2664: 'class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &__thiscall std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::
replace(unsigned int,unsigned int,const class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &)' : cannot convert parameter 3 from 'char' to 'const class std::basic_string<char,struct std::char_traits<char>,class s
td::allocator<char> > &'
Reason: cannot convert from 'char' to 'const class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >'
No constructor could take the source type, or constructor overload resolution was ambiguous