Language: C++

#include <string>
#include <iostream>

using namespace std;

int main() {
    while(1){
    char data[1200];
    cin >> data;
        if(data == '\n')break;
    //??¢??????????????????
    if(isalpha(data)){
        if(islower(data) ) cout << toupper(data);
        else cout << tolower(data);
}
    //not??¢??????????????????
    else{
            cout << data;
        }

    }
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:10:17: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
   10 |         if(data == '\n')break;
      |            ~~~~~^~~~~~~
a.cc:12:15: error: no matching function for call to 'isalpha(char [1200])'
   12 |     if(isalpha(data)){
      |        ~~~~~~~^~~~~~
In file included from /usr/include/c++/14/cctype:42,
                 from /usr/include/c++/14/bits/localefwd.h:42,
                 from /usr/include/c++/14/string:45,
                 from a.cc:1:
/usr/include/ctype.h:109:1: note: candidate: 'int isalpha(int)' (near match)
  109 | __exctype (isalpha);
      | ^~~~~~~~~
/usr/include/ctype.h:109:1: note:   conversion of argument 1 would be ill-formed:
a.cc:12:16: error: invalid conversion from 'char*' to 'int' [-fpermissive]
   12 |     if(isalpha(data)){
      |                ^~~~
      |                |
      |                char*
In file included from /usr/include/c++/14/bits/basic_ios.h:37,
                 from /usr/include/c++/14/ios:46,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:2:
/usr/include/c++/14/bits/locale_facets.h:2643:5: note: candidate: 'template<class _CharT> bool std::isalpha(_CharT, const locale&)'
 2643 |     isalpha(_CharT __c, const locale& __loc)
      |     ^~~~~~~
/usr/include/c++/14/bits/locale_facets.h:2643:5: note:   candidate expects 2 arguments, 1 provided
a.cc:13:19: error: no matching function for call to 'islower(char [1200])'
   13 |         if(islower(data) ) cout << toupper(data);
      |            ~~~~~~~^~~~~~
/usr/include/ctype.h:112:1: note: candidate: 'int islower(int)' (near match)
  112 | __exctype (islower);
      | ^~~~~~~~~
/usr/include/ctype.h:112:1: note:   conversion of argument 1 would be ill-formed:
a.cc:13:20: error: invalid conversion from 'char*' to 'int' [-fpermissive]
   13 |         if(islower(data) ) cout << toupper(data);
      |                    ^~~~
      |                    |
      |                    char*
/usr/include/c++/14/bits/locale_facets.h:2637:5: note: candidate: 'template<class _CharT> bool std::islower(_CharT, const locale&)'
 2637 |     islower(_CharT __c, const locale& __loc)
      |     ^~~~~~~
/usr/include/c++/14/bits/locale_facets.h:2637:5: note:   candidate expects 2 arguments, 1 provided
a.cc:13:43: error: no matching function for call to 'toupper(char [1200])'
   13 |         if(islower(data) ) cout << toupper(data);
      |                                    ~~~~~~~^~~~~~
/usr/include/ctype.h:125:12: note: candidate: 'int toupper(int)' (near match)
  125 | extern int toupper (int __c) __THROW;
      |            ^~~~~~~
/usr/include/ctype.h:125:12: note:   conversion of argument 1 would be ill-formed:
a.cc:13:44: error: invalid conversion from 'char*' to 'int' [-fpermissive]
   13 |         if(islower(data) ) cout << toupper(data);
      |                                            ^~~~
      |                                            |
      |                                            char*
/usr/include/c++/14/bits/locale_facets.h:2687:5: note: candidate: 'template<class _CharT> _CharT std::toupper(_CharT, const locale&)'
 2687 |     toupper(_CharT __c, const locale& __loc)
      |     ^~~~~~~
/usr/include/c++/14/bits/locale_facets.h:2687:5: note:   candidate expects 2 arguments, 1 provided
a.cc:14:29: error: no matching function for call to 'tolower(char [1200])'
   14 |         else cout << tolower(data);
      |                      ~~~~~~~^~~~~~
/usr/include/ctype.h:122:12: note: candidate: 'int tolower(int)' (near match)
  122 | extern int tolower (int __c) __THROW;
      |            ^~~~~~~
/usr/include/ctype.h:122:12: note:   conversion of argument 1 would be ill-formed:
a.cc:14:30: error: invalid conversion from 'char*' to 'int' [-fpermissive]
   14 |         else cout << tolower(data);
      |                              ^~~~
      |                              |
      |                              char*
/usr/include/c++/14/bits/locale_facets.h:2693:5: note: candidate: 'template<class _CharT> _CharT std::tolower(_CharT, const locale&)'
 2693 |     tolower(_CharT __c, const locale& __loc)
      |     ^~~~~~~
/usr/include/c++/14/bits/locale_facets.h:2693:5: note:   candidate expects 2 arguments, 1 provided