foo.cc: In function 'int main()':
foo.cc:6:8: error: no match for 'operator<<' (operand types are 'std::istream {aka std::basic_istream<char>}' and 'int')
cin<<x<<y;
~~~^~~
foo.cc:6:8: note: candidate: operator<<(int, int) <built-in>
foo.cc:6:8: note: no known conversion for argument 1 from 'std::istream {aka std::basic_istream<char>}' to 'int'
In file included from /usr/include/c++/7/string:52:0,
from /usr/include/c++/7/bits/locale_classes.h:40,
from /usr/include/c++/7/bits/ios_base.h:41,
from /usr/include/c++/7/ios:42,
from /usr/include/c++/7/ostream:38,
from /usr/include/c++/7/iostream:39,
from foo.cc:1:
/usr/include/c++/7/bits/basic_string.h:6284:5: note: candidate: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)
operator<<(basic_ostream<_CharT, _Traits>& __os,
^~~~~~~~
/usr/include/c++/7/bits/basic_string.h:6284:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<_CharT, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/bits/ios_base.h:46:0,
from /usr/include/c++/7/ios:42,
from /usr/include/c++/7/ostream:38,
from /usr/include/c++/7/iostream:39,
from foo.cc:1:
/usr/include/c++/7/system_error:217:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::error_code&)
operator<<(basic_ostream<_CharT, _Traits>& __os, const error_code& __e)
^~~~~~~~
/usr/include/c++/7/system_error:217:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<_CharT, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/iostream:39:0,
from foo.cc:1:
/usr/include/c++/7/ostream:497:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, _CharT)
operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c)
^~~~~~~~
/usr/include/c++/7/ostream:497:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<_CharT, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/iostream:39:0,
from foo.cc:1:
/usr/include/c++/7/ostream:502:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, char)
operator<<(basic_ostream<_CharT, _Traits>& __out, char __c)
^~~~~~~~
/usr/include/c++/7/ostream:502:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<_CharT, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/iostream:39:0,
from foo.cc:1:
/usr/include/c++/7/ostream:508:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, char)
operator<<(basic_ostream<char, _Traits>& __out, char __c)
^~~~~~~~
/usr/include/c++/7/ostream:508:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<char, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/iostream:39:0,
from foo.cc:1:
/usr/include/c++/7/ostream:514:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, signed char)
operator<<(basic_ostream<char, _Traits>& __out, signed char __c)
^~~~~~~~
/usr/include/c++/7/ostream:514:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<char, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/iostream:39:0,
from foo.cc:1:
/usr/include/c++/7/ostream:519:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, unsigned char)
operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c)
^~~~~~~~
/usr/include/c++/7/ostream:519:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<char, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/iostream:39:0,
from foo.cc:1:
/usr/include/c++/7/ostream:539:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const _CharT*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s)
^~~~~~~~
/usr/include/c++/7/ostream:539:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<_CharT, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/ostream:693:0,
from /usr/include/c++/7/iostream:39,
from foo.cc:1:
/usr/include/c++/7/bits/ostream.tcc:321:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const char*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s)
^~~~~~~~
/usr/include/c++/7/bits/ostream.tcc:321:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<_CharT, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/iostream:39:0,
from foo.cc:1:
/usr/include/c++/7/ostream:556:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const char*)
operator<<(basic_ostream<char, _Traits>& __out, const char* __s)
^~~~~~~~
/usr/include/c++/7/ostream:556:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<char, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/iostream:39:0,
from foo.cc:1:
/usr/include/c++/7/ostream:569:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const signed char*)
operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s)
^~~~~~~~
/usr/include/c++/7/ostream:569:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<char, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/iostream:39:0,
from foo.cc:1:
/usr/include/c++/7/ostream:574:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const unsigned char*)
operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s)
^~~~~~~~
/usr/include/c++/7/ostream:574:5: note: template argument deduction/substitution failed:
foo.cc:6:10: note: 'std::istream {aka std::basic_istream<char>}' is not derived from 'std::basic_ostream<char, _Traits>'
cin<<x<<y;
^
In file included from /usr/include/c++/7/iostream:39:0,
from foo.cc:1:
/usr/include/c++/7/ostream:682:5: note: candidate: template<class _Ostream, class _Tp> typename std::enable_if<std::__and_<std::__not_<std::is_lvalue_reference<_Tp> >, std::__is_convertible_to_basic_ostream<_Ostream>, std::__is_insertable<typename std::__is_convertible_to_basic_ostream<_Tp>::__ostream_type, const _Tp&, void> >::value, typename std::__is_convertible_to_basic_ostream<_Tp>::__ostream_type>::type std::operator<<(_Ostream&&, const _Tp&)
operator<<(_Ostream&& __os, const _Tp& __x)
^~~~~~~~
/usr/include/c++/7/ostream:682:5: note: template argument deduction/substitution failed:
/usr/include/c++/7/ostream: In substitution of 'template<class _Ostream, class _Tp> typename std::enable_if<std::__and_<std::__not_<std::is_lvalue_reference<_Tp> >, std::__is_convertible_to_basic_ostream<_Ostream>, std::__is_insertable<typename std::__is_convertible_to_basic_ostream<_Tp>::__ostream_type, const _Tp&, void> >::value, typename std::__is_convertible_to_basic_ostream<_Tp>::__ostream_type>::type std::operator<<(_Ostream&&, const _Tp&) [with _Ostream = std::basic_istream<char>&; _Tp = int]':
foo.cc:6:10: required from here
/usr/include/c++/7/ostream:682:5: error: no type named 'type' in 'struct std::enable_if<false, void>'
foo.cc:7:6: error: no match for 'operator>>' (operand types are 'std::ostream {aka std::basic_ostream<char>}' and 'int')
cout>>x+y>>endl;
~~~~^~~~~
foo.cc:7:6: note: candidate: operator>>(int, int) <built-in>
foo.cc:7:6: note: no known conversion for argument 1 from 'std::ostream {aka std::basic_ostream<char>}' to 'int'
In file included from /usr/include/c++/7/string:53:0,
from /usr/include/c++/7/bits/locale_classes.h:40,
from /usr/include/c++/7/bits/ios_base.h:41,
from /usr/include/c++/7/ios:42,
from /usr/include/c++/7/ostream:38,
from /usr/include/c++/7/iostream:39,
from foo.cc:1:
/usr/include/c++/7/bits/basic_string.tcc:1465:5: note: candidate: template<class _CharT, class _Traits, class _Alloc> 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++/7/bits/basic_string.tcc:1465:5: note: template argument deduction/substitution failed:
foo.cc:7:10: note: 'std::ostream {aka std::basic_ostream<char>}' is not derived from 'std::basic_istream<_CharT, _Traits>'
cout>>x+y>>endl;
^
In file included from /usr/include/c++/7/istream:991:0,
from /usr/include/c++/7/iostream:40,
from foo.cc:1:
/usr/include/c++/7/bits/istream.tcc:963:5: note: candidate: template<class _CharT2, class _Traits2> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT2*)
operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s)
^~~~~~~~
/usr/include/c++/7/bits/istream.tcc:963:5: note: template argument deduction/substitution failed:
foo.cc:7:10: note: 'std::ostream {aka std::basic_ostream<char>}' is not derived from 'std::basic_istream<_CharT, _Traits>'
cout>>x+y>>endl;
^
In file included from /usr/include/c++/7/istream:991:0,
from /usr/include/c++/7/iostream:40,
from foo.cc:1:
/usr/include/c++/7/bits/istream.tcc:931:5: note: candidate: template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT&)
operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c)
^~~~~~~~
/usr/include/c++/7/bits/istream.tcc:931:5: note: template argument deduction/substitution failed:
foo.cc:7:10: note: 'std::ostream {aka std::basic_ostream<char>}' is not derived from 'std::basic_istream<_CharT, _Traits>'
cout>>x+y>>endl;
^
In file included from /usr/include/c++/7/iostream:40:0,
from foo.cc:1:
/usr/include/c++/7/istream:756:5: note: candidate: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char&)
operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
^~~~~~~~
/usr/include/c++/7/istream:756:5: note: template argument deduction/substitution failed:
foo.cc:7:10: note: 'std::ostream {aka std::basic_ostream<char>}' is not derived from 'std::basic_istream<char, _Traits>'
cout>>x+y>>endl;
^
In file included from /usr/include/c++/7/iostream:40:0,
from foo.cc:1:
/usr/include/c++/7/istream:761:5: note: candidate: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char&)
operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
^~~~~~~~
/usr/include/c++/7/istream:761:5: note: template argument deduction/substitution failed:
foo.cc:7:10: note: 'std::ostream {aka std::basic_ostream<char>}' is not derived from 'std::basic_istream<char, _Traits>'
cout>>x+y>>endl;
^
In file included from /usr/include/c++/7/iostream:40:0,
from foo.cc:1:
/usr/include/c++/7/istream:803:5: note: candidate: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char*)
operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
^~~~~~~~
/usr/include/c++/7/istream:803:5: note: template argument deduction/substitution failed:
foo.cc:7:10: note: 'std::ostream {aka std::basic_ostream<char>}' is not derived from 'std::basic_istream<char, _Traits>'
cout>>x+y>>endl;
^
In file included from /usr/include/c++/7/iostream:40:0,
from foo.cc:1:
/usr/include/c++/7/istream:808:5: note: candidate: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char*)
operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
^~~~~~~~
/usr/include/c++/7/istream:808:5: note: template argument deduction/substitution failed:
foo.cc:7:10: note: 'std::ostream {aka std::basic_ostream<char>}' is not derived from 'std::basic_istream<char, _Traits>'
cout>>x+y>>endl;
^
In file included from /usr/include/c++/7/iostream:40:0,
from foo.cc:1:
/usr/include/c++/7/istream:980:5: note: candidate: template<class _Istream, class _Tp> typename std::enable_if<std::__and_<std::__not_<std::is_lvalue_reference<_Tp> >, std::__is_convertible_to_basic_istream<_Istream>, std::__is_extractable<typename std::__is_convertible_to_basic_istream<_Tp>::__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++/7/istream:980:5: note: template argument deduction/substitution failed:
/usr/include/c++/7/istream: In substitution of 'template<class _Istream, class _Tp> typename std::enable_if<std::__and_<std::__not_<std::is_lvalue_reference<_Tp> >, std::__is_convertible_to_basic_istream<_Istream>, std::__is_extractable<typename std::__is_convertible_to_basic_istream<_Tp>::__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<char>&; _Tp = int]':
foo.cc:7:10: required from here
/usr/include/c++/7/istream:980:5: error: no type named 'type' in 'struct std::enable_if<false, void>'
foo.cc:7:9: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
cout>>x+y>>endl;
~^~
202012114潘梓越 LV 3
undefined
