Language: C++

#include <iostream>
#include <cctype>

#define MAX_LEN (1200)

using namespace std;

int main()
{ 
    char* str = new char[MAX_LEN + 1];
   
    getline(str, MAX_LEN, '\n');

    for (int i = 0; str[i] != '\0'; i++) {
         if (str[i] >= 'A' && ch <= 'Z') {
             str[i] = tolower(str[i]);
         } else if (str[i] >= 'a' && ch <= 'z') {
             str[i] = toupper(str[i]);
         }  
    }                               
     
    cout << str << endl;

    delete[] str;     
	   
    return (0);
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:12: error: no matching function for call to 'getline(char*&, int, char)'
   12 |     getline(str, MAX_LEN, '\n');
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~
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:907:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
  907 |     getline(basic_istream<_CharT, _Traits>& __in,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.tcc:907:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'char*'
   12 |     getline(str, MAX_LEN, '\n');
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:54:
/usr/include/c++/14/bits/basic_string.h:4117:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 4117 |     getline(basic_istream<_CharT, _Traits>& __is,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.h:4117:5: note:   candidate expects 2 arguments, 3 provided
/usr/include/c++/14/bits/basic_string.h:4125:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
 4125 |     getline(basic_istream<_CharT, _Traits>&& __is,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.h:4125:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   mismatched types 'std::basic_istream<_CharT, _Traits>' and 'char*'
   12 |     getline(str, MAX_LEN, '\n');
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/basic_string.h:4132:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 4132 |     getline(basic_istream<_CharT, _Traits>&& __is,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.h:4132:5: note:   candidate expects 2 arguments, 3 provided
In file included from /usr/include/c++/14/cstdio:42,
                 from /usr/include/c++/14/ext/string_conversions.h:45,
                 from /usr/include/c++/14/bits/basic_string.h:4154:
/usr/include/stdio.h:697:18: note: candidate: '__ssize_t getline(char**, size_t*, FILE*)'
  697 | extern __ssize_t getline (char **__restrict __lineptr,
      |                  ^~~~~~~
/usr/include/stdio.h:697:45: note:   no known conversion for argument 1 from 'char*' to 'char**'
  697 | extern __ssize_t getline (char **__restrict __lineptr,
      |                           ~~~~~~~~~~~~~~~~~~^~~~~~~~~
a.cc:15:31: error: 'ch' was not declared in this scope
   15 |          if (str[i] >= 'A' && ch <= 'Z') {
      |                               ^~