Odd compile errors on c++ program - c++

Question

So i'm trying to make a program that reads input from the user, transforms it into a note like this:
--- time
note
Here's the code for it:
#include <iostream>
#include <fstream>
#include <ctime>
#include <cstdlib>
using namespace std;
int main () {
string notesvar{"/notes"};
string home{std::getenv("HOME")};
string notes{home, notesvar};
time_t now = time(0);
char* dt = ctime(&now);
ofstream myfile;
std::cout << ": ";
string x{};
std::cin >> x;
myfile.open ("placeholder", ios_base::app);
myfile << "---- " << dt;
myfile << x << '\n';
myfile << "\n";
myfile.close();
return 0;
}
This compiles with a lot of notes, but here's the compile log:
notes.cpp: In function ‘int main()’:
notes.cpp:9:32: error: no matching function for call to ‘std::__cxx11::basic_string<char>::basic_string(<brace-enclosed initializer list>)’
9 | string notes{home, notesvar};
| ^
In file included from /usr/include/c++/9.3.0/string:55,
from /usr/include/c++/9.3.0/bits/locale_classes.h:40,
from /usr/include/c++/9.3.0/bits/ios_base.h:41,
from /usr/include/c++/9.3.0/ios:42,
from /usr/include/c++/9.3.0/ostream:38,
from /usr/include/c++/9.3.0/iostream:39,
from notes.cpp:1:
/usr/include/c++/9.3.0/bits/basic_string.h:650:2: note: candidate: ‘template<class _Tp, class> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _Tp&, const _Alloc&)’
650 | basic_string(const _Tp& __t, const _Alloc& __a = _Alloc())
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:650:2: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/9.3.0/bits/move.h:55,
from /usr/include/c++/9.3.0/bits/nested_exception.h:40,
from /usr/include/c++/9.3.0/exception:144,
from /usr/include/c++/9.3.0/ios:39,
from /usr/include/c++/9.3.0/ostream:38,
from /usr/include/c++/9.3.0/iostream:39,
from notes.cpp:1:
/usr/include/c++/9.3.0/type_traits: In substitution of ‘template<bool _Cond, class _Tp> using enable_if_t = typename std::enable_if::type [with bool _Cond = std::integral_constant<bool, false>::value; _Tp = void]’:
/usr/include/c++/9.3.0/bits/basic_string.h:117:8: required by substitution of ‘template<class _CharT, class _Traits, class _Alloc> template<class _Tp, class _Res> using _If_sv = std::enable_if_t<std::__and_<std::is_convertible<const _Tp&, std::basic_string_view<_CharT, _Traits> >, std::__not_<std::is_convertible<const _Tp*, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>*> >, std::__not_<std::is_convertible<const _Tp&, const _CharT*> > >::value, _Res> [with _Tp = std::__cxx11::basic_string<char>; _Res = void; _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
/usr/include/c++/9.3.0/bits/basic_string.h:648:30: required from here
/usr/include/c++/9.3.0/type_traits:2384:11: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
2384 | using enable_if_t = typename enable_if<_Cond, _Tp>::type;
| ^~~~~~~~~~~
In file included from /usr/include/c++/9.3.0/string:55,
from /usr/include/c++/9.3.0/bits/locale_classes.h:40,
from /usr/include/c++/9.3.0/bits/ios_base.h:41,
from /usr/include/c++/9.3.0/ios:42,
from /usr/include/c++/9.3.0/ostream:38,
from /usr/include/c++/9.3.0/iostream:39,
from notes.cpp:1:
/usr/include/c++/9.3.0/bits/basic_string.h:639:2: note: candidate: ‘template<class _Tp, class> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _Tp&, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type, const _Alloc&)’
639 | basic_string(const _Tp& __t, size_type __pos, size_type __n,
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:639:2: note: template argument deduction/substitution failed:
notes.cpp:9:32: note: candidate expects 4 arguments, 2 provided
9 | string notes{home, notesvar};
| ^
In file included from /usr/include/c++/9.3.0/string:55,
from /usr/include/c++/9.3.0/bits/locale_classes.h:40,
from /usr/include/c++/9.3.0/bits/ios_base.h:41,
from /usr/include/c++/9.3.0/ios:42,
from /usr/include/c++/9.3.0/ostream:38,
from /usr/include/c++/9.3.0/iostream:39,
from notes.cpp:1:
/usr/include/c++/9.3.0/bits/basic_string.h:625:9: note: candidate: ‘template<class _InputIterator, class> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(_InputIterator, _InputIterator, const _Alloc&)’
625 | basic_string(_InputIterator __beg, _InputIterator __end,
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:625:9: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/9.3.0/bits/stl_algobase.h:65,
from /usr/include/c++/9.3.0/bits/char_traits.h:39,
from /usr/include/c++/9.3.0/ios:40,
from /usr/include/c++/9.3.0/ostream:38,
from /usr/include/c++/9.3.0/iostream:39,
from notes.cpp:1:
/usr/include/c++/9.3.0/bits/stl_iterator_base_types.h: In substitution of ‘template<class _InIter> using _RequireInputIter = typename std::enable_if<std::is_convertible<typename std::iterator_traits<_Iterator>::iterator_category, std::input_iterator_tag>::value>::type [with _InIter = std::__cxx11::basic_string<char>]’:
/usr/include/c++/9.3.0/bits/basic_string.h:621:9: required from here
/usr/include/c++/9.3.0/bits/stl_iterator_base_types.h:232:11: error: no type named ‘iterator_category’ in ‘struct std::iterator_traits<std::__cxx11::basic_string<char> >’
232 | using _RequireInputIter = typename
| ^~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/9.3.0/string:55,
from /usr/include/c++/9.3.0/bits/locale_classes.h:40,
from /usr/include/c++/9.3.0/bits/ios_base.h:41,
from /usr/include/c++/9.3.0/ios:42,
from /usr/include/c++/9.3.0/ostream:38,
from /usr/include/c++/9.3.0/iostream:39,
from notes.cpp:1:
/usr/include/c++/9.3.0/bits/basic_string.h:587:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&&, const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
587 | basic_string(basic_string&& __str, const _Alloc& __a)
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:587:56: note: no known conversion for argument 2 from ‘std::string’ {aka ‘std::__cxx11::basic_string<char>’} to ‘const std::allocator<char>&’
587 | basic_string(basic_string&& __str, const _Alloc& __a)
| ~~~~~~~~~~~~~~^~~
/usr/include/c++/9.3.0/bits/basic_string.h:583:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
583 | basic_string(const basic_string& __str, const _Alloc& __a)
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:583:61: note: no known conversion for argument 2 from ‘std::string’ {aka ‘std::__cxx11::basic_string<char>’} to ‘const std::allocator<char>&’
583 | basic_string(const basic_string& __str, const _Alloc& __a)
| ~~~~~~~~~~~~~~^~~
/usr/include/c++/9.3.0/bits/basic_string.h:579:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(std::initializer_list<_Tp>, const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
579 | basic_string(initializer_list<_CharT> __l, const _Alloc& __a = _Alloc())
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:579:45: note: no known conversion for argument 1 from ‘std::string’ {aka ‘std::__cxx11::basic_string<char>’} to ‘std::initializer_list<char>’
579 | basic_string(initializer_list<_CharT> __l, const _Alloc& __a = _Alloc())
| ~~~~~~~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/9.3.0/bits/basic_string.h:552:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
552 | basic_string(basic_string&& __str) noexcept
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:552:7: note: candidate expects 1 argument, 2 provided
/usr/include/c++/9.3.0/bits/basic_string.h:540:7: note: candidate: ‘template<class> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type, _CharT, const _Alloc&)’
540 | basic_string(size_type __n, _CharT __c, const _Alloc& __a = _Alloc())
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:540:7: note: template argument deduction/substitution failed:
notes.cpp:9:18: note: cannot convert ‘home’ (type ‘std::string’ {aka ‘std::__cxx11::basic_string<char>’}) to type ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’}
9 | string notes{home, notesvar};
| ^~~~
In file included from /usr/include/c++/9.3.0/string:55,
from /usr/include/c++/9.3.0/bits/locale_classes.h:40,
from /usr/include/c++/9.3.0/bits/ios_base.h:41,
from /usr/include/c++/9.3.0/ios:42,
from /usr/include/c++/9.3.0/ostream:38,
from /usr/include/c++/9.3.0/iostream:39,
from notes.cpp:1:
/usr/include/c++/9.3.0/bits/basic_string.h:525:7: note: candidate: ‘template<class> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _CharT*, const _Alloc&)’
525 | basic_string(const _CharT* __s, const _Alloc& __a = _Alloc())
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:525:7: note: template argument deduction/substitution failed:
notes.cpp:9:18: note: cannot convert ‘home’ (type ‘std::string’ {aka ‘std::__cxx11::basic_string<char>’}) to type ‘const char*’
9 | string notes{home, notesvar};
| ^~~~
In file included from /usr/include/c++/9.3.0/string:55,
from /usr/include/c++/9.3.0/bits/locale_classes.h:40,
from /usr/include/c++/9.3.0/bits/ios_base.h:41,
from /usr/include/c++/9.3.0/ios:42,
from /usr/include/c++/9.3.0/ostream:38,
from /usr/include/c++/9.3.0/iostream:39,
from notes.cpp:1:
/usr/include/c++/9.3.0/bits/basic_string.h:510:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _CharT*, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type, const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type = long unsigned int]’
510 | basic_string(const _CharT* __s, size_type __n,
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:510:34: note: no known conversion for argument 1 from ‘std::string’ {aka ‘std::__cxx11::basic_string<char>’} to ‘const char*’
510 | basic_string(const _CharT* __s, size_type __n,
| ~~~~~~~~~~~~~~^~~
/usr/include/c++/9.3.0/bits/basic_string.h:492:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type, const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type = long unsigned int]’
492 | basic_string(const basic_string& __str, size_type __pos,
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:492:7: note: candidate expects 4 arguments, 2 provided
/usr/include/c++/9.3.0/bits/basic_string.h:476:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type = long unsigned int]’
476 | basic_string(const basic_string& __str, size_type __pos,
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:476:7: note: candidate expects 3 arguments, 2 provided
/usr/include/c++/9.3.0/bits/basic_string.h:461:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type, const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type = long unsigned int]’
461 | basic_string(const basic_string& __str, size_type __pos,
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:461:57: note: no known conversion for argument 2 from ‘std::string’ {aka ‘std::__cxx11::basic_string<char>’} to ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’}
461 | basic_string(const basic_string& __str, size_type __pos,
| ~~~~~~~~~~^~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:448:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
448 | basic_string(const basic_string& __str)
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:448:7: note: candidate expects 1 argument, 2 provided
/usr/include/c++/9.3.0/bits/basic_string.h:440:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
440 | basic_string(const _Alloc& __a) _GLIBCXX_NOEXCEPT
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:440:7: note: candidate expects 1 argument, 2 provided
/usr/include/c++/9.3.0/bits/basic_string.h:431:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string() [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
431 | basic_string()
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:431:7: note: candidate expects 0 arguments, 2 provided
/usr/include/c++/9.3.0/bits/basic_string.h:145:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::__sv_wrapper, const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
145 | basic_string(__sv_wrapper __svw, const _Alloc& __a)
| ^~~~~~~~~~~~
/usr/include/c++/9.3.0/bits/basic_string.h:145:33: note: no known conversion for argument 1 from ‘std::string’ {aka ‘std::__cxx11::basic_string<char>’} to ‘std::__cxx11::basic_string<char>::__svT_wrapper’
145 | basic_string(__sv_wrapper __svw, const _Alloc& __a)
|
It was compiled using g++ -std=c++17 -o notes notes.cpp. Sorry if this is a stupid question. I'm just beginning with C++.
What confuses me is the error on... line 232?! Thanks in advance for helping!

Answer 1

string notes{home, notesvar};
There is no std::string(std::string, std::string) constructor. To construct another string as concatenation of two other strings, just operator + add them.
string notes = home + notesvar;