Language: C++

#include<iostream>
using namespace std;

int main()
{
  int a,b,c,d,N;
  cin >> N;
  a=N/1000;
  b=N/100 - 10*a;
  c=N/10 - 100*a - 10*b;
  d=N-1000*1 -100*b -10*c;

  int i,j,k.l;
  for(i=0;i++;i<2)
    {
      for(j=0;j++;j<2)
	{
	  for(k=0;k++;k<2)
	    {      
	      l=i*b+j*c+k*d;
	      if(a+b+c+d-2*l==7)
		{
		  break;
		}
	    }
	}
    }
  string op1,op2,op3;
  if(i==0)
    {
      op1="+";
    }
  else
    {
      op1="-";
    }
  if(j==0)
    {
      op2="+";
    }
  else
    {
      op2="-";
    }
  if(k==0)
    {
      op3="+";
    }
  else
    {
      op3="-";
    }
  cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"


Compiler output:
a.cc: In function 'int main()':
a.cc:13:12: error: expected initializer before '.' token
   13 |   int i,j,k.l;
      |            ^
a.cc:18:15: error: 'k' was not declared in this scope
   18 |           for(k=0;k++;k<2)
      |               ^
a.cc:20:15: error: 'l' was not declared in this scope
   20 |               l=i*b+j*c+k*d;
      |               ^
a.cc:45:6: error: 'k' was not declared in this scope
   45 |   if(k==0)
      |      ^
a.cc:53:7: error: no match for 'operator>>' (operand types are 'std::ostream' {aka 'std::basic_ostream<char>'} and 'int')
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |   ~~~~^~~
      |   |     |
      |   |     int
      |   std::ostream {aka std::basic_ostream<char>}
a.cc:53:7: note: candidate: 'operator>>(int, int)' (built-in)
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |   ~~~~^~~
a.cc:53:7: note:   no known conversion for argument 1 from 'std::ostream' {aka 'std::basic_ostream<char>'} to 'int'
In file included from /usr/include/c++/14/string:55,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/basic_string.tcc:835:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
  835 |     operator>>(basic_istream<_CharT, _Traits>& __in,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.tcc:835:5: note:   template argument deduction/substitution failed:
a.cc:53:9: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |         ^
In file included from /usr/include/c++/14/bits/memory_resource.h:38,
                 from /usr/include/c++/14/string:68:
/usr/include/c++/14/cstddef:131:5: note: candidate: 'template<class _IntegerType> constexpr std::__byte_op_t<_IntegerType> std::operator>>(byte, _IntegerType)'
  131 |     operator>>(byte __b, _IntegerType __shift) noexcept
      |     ^~~~~~~~
/usr/include/c++/14/cstddef:131:5: note:   template argument deduction/substitution failed:
a.cc:53:3: note:   cannot convert 'std::cout' (type 'std::ostream' {aka 'std::basic_ostream<char>'}) to type 'std::byte'
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |   ^~~~
In file included from /usr/include/c++/14/istream:1109,
                 from /usr/include/c++/14/iostream:42:
/usr/include/c++/14/bits/istream.tcc:978:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _CharT&)'
  978 |     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c)
      |     ^~~~~~~~
/usr/include/c++/14/bits/istream.tcc:978:5: note:   template argument deduction/substitution failed:
a.cc:53:9: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |         ^
/usr/include/c++/14/istream:849:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, unsigned char&)'
  849 |     operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
      |     ^~~~~~~~
/usr/include/c++/14/istream:849:5: note:   template argument deduction/substitution failed:
a.cc:53:9: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<char, _Traits>'
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |         ^
/usr/include/c++/14/istream:854:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, signed char&)'
  854 |     operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
      |     ^~~~~~~~
/usr/include/c++/14/istream:854:5: note:   template argument deduction/substitution failed:
a.cc:53:9: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<char, _Traits>'
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |         ^
/usr/include/c++/14/istream:896:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _CharT*)'
  896 |     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:896:5: note:   template argument deduction/substitution failed:
a.cc:53:9: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |         ^
/usr/include/c++/14/istream:939:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, unsigned char*)'
  939 |     operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:939:5: note:   template argument deduction/substitution failed:
a.cc:53:9: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<char, _Traits>'
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |         ^
/usr/include/c++/14/istream:945:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, signed char*)'
  945 |     operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:945:5: note:   template argument deduction/substitution failed:
a.cc:53:9: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<char, _Traits>'
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |         ^
/usr/include/c++/14/istream:1099:5: note: candidate: 'template<class _Istream, class _Tp> _Istream&& std::operator>>(_Istream&&, _Tp&&)'
 1099 |     operator>>(_Istream&& __is, _Tp&& __x)
      |     ^~~~~~~~
/usr/include/c++/14/istream:1099:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/istream: In substitution of 'template<class _Istream, class _Tp> _Istream&& std::operator>>(_Istream&&, _Tp&&) [with _Istream = std::basic_ostream<char>&; _Tp = int&]':
a.cc:53:9:   required from here
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |         ^
/usr/include/c++/14/istream:1099:5: error: no type named 'type' in 'struct std::enable_if<false, void>'
 1099 |     operator>>(_Istream&& __is, _Tp&& __x)
      |     ^~~~~~~~
a.cc:53:40: error: expected '}' at end of input
   53 |   cout>>a>>op1>>b>>op2>>c>>op3>>d>>"=7"
      |                                        ^
a.cc:5:1: note: to match this '{'
    5 | {
      | ^