Language: C++

#include <iostream>
#include <string>
#include <stdio.h>
#include <cstdio>
#include <algorithm>
using namespace std;

int main(){
    int n;
    cin >> n;
    while( n-- ){
        string p, m;
        cin >> p >> m;
        reverse( p.begin(), p.end() );
        for( size_t i = 0; i < p.length(); i++ ){
            switch(p[i]){
                case 'J':{
                    char tmp = m[m.length() - 1];
                    for( size_t j = m.length() - 1; j > 0; j-- ){
                        //if( j == 0 ){
                        //}else{
                            m[j] = m[j-1];
                        //}
                        //cout << m[j] << endl;
                    }
                    m[0] = tmp;
                    break;
                }case 'C':{
                    char tmp = m[0];
                    for( size_t j = 0; j < m.length(); j++ ){
                        if( j == m.length() - 1 ) m[j] = tmp;
                        else m[j] = m[j+1];
                    }
                    break;
                }case 'E':{
                    string tmp = m.substr( 0, m.length() / 2 );
                    m.replace( 0, (m.length() - 1) / 2, m );
                    m.append( m.length() / 2, tmp );
                    break;
                }case 'A':{
                    reverse( m.begin(), m.end() );
                    break;
                }case 'P':{
                    for( size_t j = 0; j < m.length(); j++ ){
                        if( '1' <= m[j] && m[j] <= '9' ){
                            m[j]--;
                        }else if( '0' == m[j] ){
                            m[j] = '9';
                        }
                    }
                    break;
                }case 'M':{
                    for( size_t j = 0; j < m.length(); j++ ){
                        if( '0' <= m[j] && m[j] <= '8' ){
                            m[j]++;
                        }else if( '9' == m[j] ){
                            m[j] = '0';
                        }
                    }
                    break;
                }
            }
        }
        cout << m << endl;
    }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:38:29: error: no matching function for call to 'std::__cxx11::basic_string<char>::append(std::__cxx11::basic_string<char>::size_type, std::string&)'
   38 |                     m.append( m.length() / 2, tmp );
      |                     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:54,
                 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.h:1466:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; size_type = long unsigned int]'
 1466 |       append(const _CharT* __s, size_type __n)
      |       ^~~~~~
/usr/include/c++/14/bits/basic_string.h:1466:43: note:   no known conversion for argument 2 from 'std::string' {aka 'std::__cxx11::basic_string<char>'} to 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
 1466 |       append(const _CharT* __s, size_type __n)
      |                                 ~~~~~~~~~~^~~
/usr/include/c++/14/bits/basic_string.h:1529:9: note: candidate: 'template<class _InputIterator, class> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(_InputIterator, _InputIterator) [with <template-parameter-2-2> = _InputIterator; _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
 1529 |         append(_InputIterator __first, _InputIterator __last)
      |         ^~~~~~
/usr/include/c++/14/bits/basic_string.h:1529:9: note:   template argument deduction/substitution failed:
a.cc:38:29: note:   deduced conflicting types for parameter '_InputIterator' ('long unsigned int' and 'std::__cxx11::basic_string<char>')
   38 |                     m.append( m.length() / 2, tmp );
      |                     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/basic_string.h:1541:9: note: candidate: 'template<class _Tp> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_If_sv<_Tp, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(const _Tp&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
 1541 |         append(const _Tp& __svt)
      |         ^~~~~~
/usr/include/c++/14/bits/basic_string.h:1541:9: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/basic_string.h:1557:9: note: candidate: 'template<class _Tp> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_If_sv<_Tp, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&> std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(const _Tp&, size_type, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
 1557 |         append(const _Tp& __svt, size_type __pos, size_type __n = npos)
      |         ^~~~~~
/usr/include/c++/14/bits/basic_string.h:1557:9: note:   template argument deduction/substitution failed:
a.cc:38:47: note:   cannot convert 'tmp' (type 'std::string' {aka 'std::__cxx11::basic_string<char>'}) to type 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   38 |                     m.append( m.length() / 2, tmp );
      |                                               ^~~
/usr/include/c++/14/bits/basic_string.h:1435:7: 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>]'
 1435 |       append(const basic_string& __str)
      |       ^~~~~~
/usr/include/c++/14/bits/basic_string.h:1435:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/basic_string.h:1453:7: 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>&, size_type, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; size_type = long unsigned int]'
 1453 |       append(const basic_string& __str, size_type __pos, size_type __n = npos)
      |       ^~~~~~
/usr/include/c++/14/bits/basic_string.h:1453:34: note:   no known conversion for argument 1 from 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} to 'const std::__cxx11::basic_string<char>&'
 1453 |       append(const basic_string& __str, size_type __pos, size_type __n = npos)
      |              ~~~~~~~~~~~~~~~~~~~~^~~~~
/usr/include/c++/14/bits/basic_string.h:1480:7: 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>]'
 1480 |       append(const _CharT* __s)
      |       ^~~~~~
/usr/include/c++/14/bits/basic_string.h:1480:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/basic_string.h:1498:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(size_type, _CharT) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; size_type = long unsigned int]'
 1498 |       append(size_type __n, _CharT __c)
      |       ^~~~~~
/usr/include/c++/14/bits/basic_string.h:1498:36: note:   no known conversion for argument 2 from 'std::string' {aka 'std::__cxx11::basic_string<char>'} to 'char'
 1498 |       append(size_type __n, _CharT __c)
      |                             ~~~~~~~^~~
/usr/include/c++/14/bits/basic_string.h:1509:7: 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>]'
 1509 |       append(initializer_list<_CharT> __l)
      |       ^~~~~~
/usr/include/c++/14/bits/basic_string.h:1509:7: note:   candidate expects 1 argument, 2 provided