C++ example error message

error.txt

persistent.cpp: In function ‘size_t v2s(std::string&, int)’:
persistent.cpp:184:15: error: no matching function for call to ‘std::__cxx11::basic_string<char>::append(int&)’
  184 |     s.append(v);
      |               ^
In file included from /usr/include/c++/9/string:55,
                 from /usr/include/c++/9/bits/locale_classes.h:40,
                 from /usr/include/c++/9/bits/ios_base.h:41,
                 from /usr/include/c++/9/ios:42,
                 from /usr/include/c++/9/ostream:38,
                 from /usr/include/c++/9/iostream:39,
                 from persistent.cpp:25:
/usr/include/c++/9/bits/basic_string.h:1263:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ <near match>
 1263 |       append(const _CharT* __s)
      |       ^~~~~~
/usr/include/c++/9/bits/basic_string.h:1263:7: note:   conversion of argument 1 would be ill-formed:
persistent.cpp:184:14: error: invalid conversion from ‘int’ to ‘const char*’ [-fpermissive]
  184 |     s.append(v);
      |              ^
      |              |
      |              int
In file included from /usr/include/c++/9/string:55,
                 from /usr/include/c++/9/bits/locale_classes.h:40,
                 from /usr/include/c++/9/bits/ios_base.h:41,
                 from /usr/include/c++/9/ios:42,
                 from /usr/include/c++/9/ostream:38,
                 from /usr/include/c++/9/iostream:39,
                 from persistent.cpp:25:
/usr/include/c++/9/bits/basic_string.h:1221:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
 1221 |       append(const basic_string& __str)
      |       ^~~~~~
/usr/include/c++/9/bits/basic_string.h:1221:34: note:   no known conversion for argument 1 from ‘int’ to ‘const std::__cxx11::basic_string<char>&’
 1221 |       append(const basic_string& __str)
      |              ~~~~~~~~~~~~~~~~~~~~^~~~~
/usr/include/c++/9/bits/basic_string.h:1238:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(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]’
 1238 |       append(const basic_string& __str, size_type __pos, size_type __n = npos)
      |       ^~~~~~
/usr/include/c++/9/bits/basic_string.h:1238:7: note:   candidate expects 3 arguments, 1 provided
/usr/include/c++/9/bits/basic_string.h:1250:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(const _CharT*, 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]’
 1250 |       append(const _CharT* __s, size_type __n)
      |       ^~~~~~
/usr/include/c++/9/bits/basic_string.h:1250:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/9/bits/basic_string.h:1280:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type, _CharT) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type = long unsigned int]’
 1280 |       append(size_type __n, _CharT __c)
      |       ^~~~~~
/usr/include/c++/9/bits/basic_string.h:1280:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/9/bits/basic_string.h:1290:7: note: candidate: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(std::initializer_list<_Tp>) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
 1290 |       append(initializer_list<_CharT> __l)
      |       ^~~~~~
/usr/include/c++/9/bits/basic_string.h:1290:39: note:   no known conversion for argument 1 from ‘int’ to ‘std::initializer_list<char>’
 1290 |       append(initializer_list<_CharT> __l)
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/9/bits/basic_string.h:1309:9: note: candidate: ‘template<class _InputIterator, class> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(_InputIterator, _InputIterator) [with _InputIterator = _InputIterator; <template-parameter-2-2> = <template-parameter-1-2>; _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’
 1309 |         append(_InputIterator __first, _InputIterator __last)
      |         ^~~~~~
/usr/include/c++/9/bits/basic_string.h:1309:9: note:   template argument deduction/substitution failed:
persistent.cpp:184:15: note:   candidate expects 2 arguments, 1 provided
  184 |     s.append(v);
      |               ^