Language: C++

#include<bits/stdc++.h>
using namespace std;

int main() {
  int H,W;
  cin >> H >> W;
  
  vector<vector<char>> vec(H,vector<char>(W,'-'));
  for(int i = 0; i < H; i++) {
    for(int j = 0; j < W; j++) {
      cin >> vec.at(i).at(j);
    }
  }
  
  for(int i = 0; i < vec.size(); i++) {
    if(vec.at(i) = '#') {
      continue;
    }
    if(vec.at(vec.at(0).size()) == '.') {
   for(int k = 0; k < vec.at(0).size(); k++) {
      pop_back(vec.at(i).at(k));
    } 
  }
  
  for(int j = 0; j < vec.at(0).size(); j++) {
	 if(vec.at(j) == '#') {
      continue;
    }
    if(vec.at(vec.size()) == '.') {
      for(int k = 0; k < vec.size(); k++) {
      pop_back(vec.at(k).at(j));
      }
    }  	
  }
  
  for(int i = 0; i < vec.size(); i++) {
    for(int j = 0; j < vec.at(0).size(); j++) {
    cout << vec.at(i).at(j) << endl;
    }
  cout << endl;
  }
}


Compiler output:
a.cc: In function 'int main()':
a.cc:16:20: error: no match for 'operator=' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<std::vector<char> >, std::vector<char> >::value_type' {aka 'std::vector<char>'} and 'char')
   16 |     if(vec.at(i) = '#') {
      |                    ^~~
In file included from /usr/include/c++/14/vector:72,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/vector.tcc:210:5: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(const std::vector<_Tp, _Alloc>&) [with _Tp = char; _Alloc = std::allocator<char>]'
  210 |     vector<_Tp, _Alloc>::
      |     ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/vector.tcc:211:42: note:   no known conversion for argument 1 from 'char' to 'const std::vector<char>&'
  211 |     operator=(const vector<_Tp, _Alloc>& __x)
      |               ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from /usr/include/c++/14/vector:66:
/usr/include/c++/14/bits/stl_vector.h:766:7: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(std::vector<_Tp, _Alloc>&&) [with _Tp = char; _Alloc = std::allocator<char>]'
  766 |       operator=(vector&& __x) noexcept(_Alloc_traits::_S_nothrow_move())
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:766:26: note:   no known conversion for argument 1 from 'char' to 'std::vector<char>&&'
  766 |       operator=(vector&& __x) noexcept(_Alloc_traits::_S_nothrow_move())
      |                 ~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:788:7: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(std::initializer_list<_Tp>) [with _Tp = char; _Alloc = std::allocator<char>]'
  788 |       operator=(initializer_list<value_type> __l)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:788:46: note:   no known conversion for argument 1 from 'char' to 'std::initializer_list<char>'
  788 |       operator=(initializer_list<value_type> __l)
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
a.cc:19:33: error: no match for 'operator==' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<std::vector<char> >, std::vector<char> >::value_type' {aka 'std::vector<char>'} and 'char')
   19 |     if(vec.at(vec.at(0).size()) == '.') {
      |        ~~~~~~~~~~~~~~~~~~~~~~~~ ^~ ~~~
      |              |                     |
      |              |                     char
      |              __gnu_cxx::__alloc_traits<std::allocator<std::vector<char> >, std::vector<char> >::value_type {aka std::vector<char>}
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181:
/usr/include/c++/14/bits/regex.h:1103:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1103 |     operator==(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1103:5: note:   template argument deduction/substitution failed:
a.cc:19:36: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<char> >, std::vector<char> >::value_type' {aka 'std::vector<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   19 |     if(vec.at(vec.at(0).size()) == '.') {
      |                                    ^~~
/usr/include/c++/14/bits/regex.h:1199:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1199 |     operator==(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1199:5: note:   template argument deduction/substitution failed:
a.cc:19:36: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<char> >, std::vector<char> >::value_type' {aka 'std::vector<char>'} is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   19 |     if(vec.at(vec.at(0).size()) == '.') {
      |                                    ^~~
/usr/include/c++/14/bits/regex.h:1274:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1274 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1274:5: note:   template argument deduction/substitution failed:
a.cc:19:36: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<char> >, std::vector<char> >::value_type' {aka 'std::vector<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   19 |     if(vec.at(vec.at(0).size()) == '.') {
      |                                    ^~~
/usr/include/c++/14/bits/regex.h:1366:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1366 |     operator==(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1366:5: note:   template argument deduction/substitution failed:
a.cc:19:36: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'char'
   19 |     if(vec.at(vec.at(0).size()) == '.') {
      |                                    ^~~
/usr/include/c++/14/bits/regex.h:1441:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1441 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1441:5: note:   template argument deduction/substitution failed:
a.cc:19:36: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<char> >, std::vector<char> >::value_type' {aka 'std::vector<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   19 |     if(vec.at(vec.at(0).size()) == '.') {
      |                                    ^~~
/usr/include/c++/14/bits/regex.h:1534:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1534 |     operator==(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1534:5: note:   template argument deduction/substitution failed:
a.cc:19:36: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'char'
   19 |     if(vec.at(vec.at(0).size()) == '.') {
      |                                    ^~~
/usr/include/c++/14/bits/regex.h:1613:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1613 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1613:5: note:   template argument deduction/substitution failed:
a.cc:19:36: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<char> >, std::vector<char> >::value_type' {aka 'std::vector<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   19 |     if(vec.at(vec.at(0).size()) == '.') {
      |                                    ^~~
/usr/include/c++/14/bits/regex.h:2186:5: note: candidate: 'template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator==(const match_results<_BiIter, _Alloc>&, const match_results<_BiIter, _Alloc>&)'
 2186 |     operator==(const match_results<_Bi_iter, _Alloc>& __m1,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:2186:5: note:   template argument deduction/substitution failed:
a.cc:19:36: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<char> >, std::vector<char> >::value_type' {aka 'std::vector<char>'} is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
   19 |     if(vec.at(vec.at(0).size()) == '.') {
      |                                    ^~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_pair.h:1033:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1033 |     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1033:5: note:   template argument deduction/substitution failed:
a.cc:19:36: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<char> >, std::vector<char> >::value_type' {aka 'std::vector<char>'} is not derived from 'const std::pair<_T1, _T2>'
   19 |     if(vec.at(vec.at(0).size()) == '.') {
      |                                    ^~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:441:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  441 |     operator==(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:441:5: note:   template argument deduction/substitution failed:
a.cc:19:36: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::vector<char> >, std::vector<char> >::value_type' {aka 'std::vector<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   19 |     if(vec.at(vec.at(0).size()) == '.') {
      |                                    ^~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  486 |     operator==(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note:   template argument deduction/substitution failed:
a.cc:19:36: note:   '__gnu_cxx::__allo