运行 ID: 1

Main.cc: 在函数‘int maint()’中:
Main.cc:6:10: 错误：no match for ‘operator>>’ (operand types are ‘std::ostream’ {aka ‘std::basic_ostream’} and ‘int’)
     cout >> a+b;
     ~~~~~^~~~~~
Main.cc:6:10: 附注：candidate: ‘operator>>(int, int)’ 
Main.cc:6:10: 附注：  no known conversion for argument 1 from ‘std::ostream’ {aka ‘std::basic_ostream’} to ‘int’
In file included from /usr/include/c++/8/string:53,
                 from /usr/include/c++/8/bits/locale_classes.h:40,
                 from /usr/include/c++/8/bits/ios_base.h:41,
                 from /usr/include/c++/8/ios:42,
                 from /usr/include/c++/8/ostream:38,
                 from /usr/include/c++/8/iostream:39,
                 from Main.cc:1:
/usr/include/c++/8/bits/basic_string.tcc:1465:5: 附注：candidate: ‘template std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)’
     operator>>(basic_istream<_CharT, _Traits>& __in,
     ^~~~~~~~
/usr/include/c++/8/bits/basic_string.tcc:1465:5: 附注：  template argument deduction/substitution failed:
Main.cc:6:15: 附注：  ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘std::basic_istream<_CharT, _Traits>’
     cout >> a+b;
               ^
In file included from /usr/include/c++/8/istream:991,
                 from /usr/include/c++/8/iostream:40,
                 from Main.cc:1:
/usr/include/c++/8/bits/istream.tcc:931:5: 附注：candidate: ‘template std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT&)’
     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c)
     ^~~~~~~~
/usr/include/c++/8/bits/istream.tcc:931:5: 附注：  template argument deduction/substitution failed:
Main.cc:6:15: 附注：  ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘std::basic_istream<_CharT, _Traits>’
     cout >> a+b;
               ^
In file included from /usr/include/c++/8/iostream:40,
                 from Main.cc:1:
/usr/include/c++/8/istream:756:5: 附注：candidate: ‘template std::basic_istream& std::operator>>(std::basic_istream&, unsigned char&)’
     operator>>(basic_istream& __in, unsigned char& __c)
     ^~~~~~~~
/usr/include/c++/8/istream:756:5: 附注：  template argument deduction/substitution failed:
Main.cc:6:15: 附注：  ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘std::basic_istream’
     cout >> a+b;
               ^
In file included from /usr/include/c++/8/iostream:40,
                 from Main.cc:1:
/usr/include/c++/8/istream:761:5: 附注：candidate: ‘template std::basic_istream& std::operator>>(std::basic_istream&, signed char&)’
     operator>>(basic_istream& __in, signed char& __c)
     ^~~~~~~~
/usr/include/c++/8/istream:761:5: 附注：  template argument deduction/substitution failed:
Main.cc:6:15: 附注：  ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘std::basic_istream’
     cout >> a+b;
               ^
In file included from /usr/include/c++/8/istream:991,
                 from /usr/include/c++/8/iostream:40,
                 from Main.cc:1:
/usr/include/c++/8/bits/istream.tcc:963:5: 附注：candidate: ‘template std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT2*)’
     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s)
     ^~~~~~~~
/usr/include/c++/8/bits/istream.tcc:963:5: 附注：  template argument deduction/substitution failed:
Main.cc:6:15: 附注：  ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘std::basic_istream<_CharT, _Traits>’
     cout >> a+b;
               ^
In file included from /usr/include/c++/8/iostream:40,
                 from Main.cc:1:
/usr/include/c++/8/istream:803:5: 附注：candidate: ‘template std::basic_istream& std::operator>>(std::basic_istream&, unsigned char*)’
     operator>>(basic_istream& __in, unsigned char* __s)
     ^~~~~~~~
/usr/include/c++/8/istream:803:5: 附注：  template argument deduction/substitution failed:
Main.cc:6:15: 附注：  ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘std::basic_istream’
     cout >> a+b;
               ^
In file included from /usr/include/c++/8/iostream:40,
                 from Main.cc:1:
/usr/include/c++/8/istream:808:5: 附注：candidate: ‘template std::basic_istream& std::operator>>(std::basic_istream&, signed char*)’
     operator>>(basic_istream& __in, signed char* __s)
     ^~~~~~~~
/usr/include/c++/8/istream:808:5: 附注：  template argument deduction/substitution failed:
Main.cc:6:15: 附注：  ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘std::basic_istream’
     cout >> a+b;
               ^
In file included from /usr/include/c++/8/iostream:40,
                 from Main.cc:1:
/usr/include/c++/8/istream:980:5: 附注：candidate: ‘template typename std::enable_if >, std::__is_convertible_to_basic_istream<_Istream>, std::__is_extractable::__istream_type, _Tp&&, void> >::value, typename std::__is_convertible_to_basic_istream<_Tp>::__istream_type>::type std::operator>>(_Istream&&, _Tp&&)’
     operator>>(_Istream&& __is, _Tp&& __x)
     ^~~~~~~~
/usr/include/c++/8/istream:980:5: 附注：  template argument deduction/substitution failed:
/usr/include/c++/8/istream: In substitution of ‘template typename std::enable_if >, std::__is_convertible_to_basic_istream<_Istream>, std::__is_extractable::__istream_type, _Tp&&, void> >::value, typename std::__is_convertible_to_basic_istream<_Tp>::__istream_type>::type std::operator>>(_Istream&&, _Tp&&) [with _Istream = std::basic_ostream&; _Tp = int]’:
Main.cc:6:15:   required from here
/usr/include/c++/8/istream:980:5: 错误：no type named ‘type’ in ‘struct std::enable_if’
Main.cc:6:14: 警告：建议在‘>>’的操作数中出现的‘+’前后加上括号 [-Wparentheses]
     cout >> a+b;
             ~^~
Main.cc:7:1: 警告：在有返回值的函数中未发现 return 语句 [-Wreturn-type]
 }
 ^