Tengo una posible solución PROVISIONAL aunque puede desbordar:

#include<iostream>
#include <cstring>
using namespace std;
 
 
bool cod_aux(string &s);
void cod(string &s);
 
 
int main()
{ 
 
  string j = "áóÁsÚíu";
  cod(j);
  cout << endl << j;//-> aoAsUiu
}
 
 
void cod(string &s)
{
  string aux = "";
  string aux2 = "";
  bool add = false;
  char auxc;
  for(int i = 0; i < s.length(); i++)
  {
    aux +=s[i];
    aux +=s[i+1];
    if(cod_aux(aux) == false)
    {
     aux2 += aux;
     i = i +1;
    }
    else aux2 +=s[i];
 
      aux = ""; 
  }
    s = aux2;
}
 
 
bool cod_aux(string &s)
{
  string aux = s;
  if(s == "á")
    s = "a";
  if(s == "Á")
     s = "A";
  if(s == "é")
    s = "e";
  if(s == "É")
     s = "E";
  if(s == "í")
    s = "i";
  if(s == "Í")
    s = "I"; 
  if(s == "Ó")
     s = "O";    
  if(s == "ó")
     s = "o";
  if(s == "Ú")
     s = "U";    
  if(s == "ú")
     s = "u"; 
   return aux == s;
}
 

  string s = "á";
  if(s == 'á')
    cout << "\nok";
 

el error:
a.cc:14:11: warning: multi-character character constant [-Wmultichar]
   if(s == 'á')
           ^
a.cc: In function ‘int main()’:
a.cc:14:8: error: no match for ‘operator==’ (operand types are ‘std::string {aka std::basic_string<char>}’ and ‘int’)
   if(s == 'á')
        ^
a.cc:14:8: note: candidates are:
In file included from /usr/include/c++/4.8/iosfwd:40:0,
                 from /usr/include/c++/4.8/ios:38,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/postypes.h:216:5: note: template<class _StateT> bool std::operator==(const std::fpos<_StateT>&, const std::fpos<_StateT>&)
     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
     ^
/usr/include/c++/4.8/bits/postypes.h:216:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   ‘std::string {aka std::basic_string<char>}’ is not derived from ‘const std::fpos<_StateT>’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/bits/stl_algobase.h:64:0,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/stl_pair.h:214:5: note: template<class _T1, class _T2> bool std::operator==(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)
     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
     ^
/usr/include/c++/4.8/bits/stl_pair.h:214:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   ‘std::string {aka std::basic_string<char>}’ is not derived from ‘const std::pair<_T1, _T2>’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/stl_iterator.h:291:5: note: template<class _Iterator> bool std::operator==(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)
     operator==(const reverse_iterator<_Iterator>& __x,
     ^
/usr/include/c++/4.8/bits/stl_iterator.h:291:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   ‘std::string {aka std::basic_string<char>}’ is not derived from ‘const std::reverse_iterator<_Iterator>’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/stl_iterator.h:341:5: note: template<class _IteratorL, class _IteratorR> bool std::operator==(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&)
     operator==(const reverse_iterator<_IteratorL>& __x,
     ^
/usr/include/c++/4.8/bits/stl_iterator.h:341:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   ‘std::string {aka std::basic_string<char>}’ is not derived from ‘const std::reverse_iterator<_Iterator>’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/string:41:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/allocator.h:128:5: note: template<class _T1, class _T2> bool std::operator==(const std::allocator<_CharT>&, const std::allocator<_T2>&)
     operator==(const allocator<_T1>&, const allocator<_T2>&)
     ^
/usr/include/c++/4.8/bits/allocator.h:128:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   ‘std::string {aka std::basic_string<char>}’ is not derived from ‘const std::allocator<_CharT>’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/string:41:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/allocator.h:133:5: note: template<class _Tp> bool std::operator==(const std::allocator<_CharT>&, const std::allocator<_CharT>&)
     operator==(const allocator<_Tp>&, const allocator<_Tp>&)
     ^
/usr/include/c++/4.8/bits/allocator.h:133:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   ‘std::string {aka std::basic_string<char>}’ is not derived from ‘const std::allocator<_CharT>’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/string:52:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/basic_string.h:2486:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const std::basic_string<_CharT, _Traits, _Alloc>&, const std::basic_string<_CharT, _Traits, _Alloc>&)
     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
     ^
/usr/include/c++/4.8/bits/basic_string.h:2486:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   mismatched types ‘const std::basic_string<_CharT, _Traits, _Alloc>’ and ‘int’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/string:52:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/basic_string.h:2493:5: note: template<class _CharT> typename __gnu_cxx::__enable_if<std::__is_char<_Tp>::__value, bool>::__type std::operator==(const std::basic_string<_CharT>&, const std::basic_string<_CharT>&)
     operator==(const basic_string<_CharT>& __lhs,
     ^
/usr/include/c++/4.8/bits/basic_string.h:2493:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   mismatched types ‘const std::basic_string<_CharT>’ and ‘int’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/string:52:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/basic_string.h:2507:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const _CharT*, const std::basic_string<_CharT, _Traits, _Alloc>&)
     operator==(const _CharT* __lhs,
     ^
/usr/include/c++/4.8/bits/basic_string.h:2507:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   mismatched types ‘const _CharT*’ and ‘std::basic_string<char>’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/string:52:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/basic_string.h:2519:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const std::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*)
     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
     ^
/usr/include/c++/4.8/bits/basic_string.h:2519:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   mismatched types ‘const _CharT*’ and ‘int’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/bits/locale_facets.h:48:0,
                 from /usr/include/c++/4.8/bits/basic_ios.h:37,
                 from /usr/include/c++/4.8/ios:44,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/streambuf_iterator.h:204:5: note: template<class _CharT, class _Traits> bool std::operator==(const std::istreambuf_iterator<_CharT, _Traits>&, const std::istreambuf_iterator<_CharT, _Traits>&)
     operator==(const istreambuf_iterator<_CharT, _Traits>& __a,
     ^
/usr/include/c++/4.8/bits/streambuf_iterator.h:204:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   ‘std::string {aka std::basic_string<char>}’ is not derived from ‘const std::istreambuf_iterator<_CharT, _Traits>’
   if(s == 'á')
           ^
In file included from /usr/include/x86_64-linux-gnu/c++/4.8/bits/c++allocator.h:33:0,
                 from /usr/include/c++/4.8/bits/allocator.h:46,
                 from /usr/include/c++/4.8/string:41,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/ext/new_allocator.h:139:5: note: template<class _Tp> bool __gnu_cxx::operator==(const __gnu_cxx::new_allocator<_Tp>&, const __gnu_cxx::new_allocator<_Tp>&)
     operator==(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
     ^
/usr/include/c++/4.8/ext/new_allocator.h:139:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   ‘std::string {aka std::basic_string<char>}’ is not derived from ‘const __gnu_cxx::new_allocator<_Tp>’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/stl_iterator.h:811:5: note: template<class _Iterator, class _Container> bool __gnu_cxx::operator==(const __gnu_cxx::__normal_iterator<_Iterator, _Container>&, const __gnu_cxx::__normal_iterator<_Iterator, _Container>&)
     operator==(const __normal_iterator<_Iterator, _Container>& __lhs,
     ^
/usr/include/c++/4.8/bits/stl_iterator.h:811:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   ‘std::string {aka std::basic_string<char>}’ is not derived from ‘const __gnu_cxx::__normal_iterator<_Iterator, _Container>’
   if(s == 'á')
           ^
In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from a.cc:1:
/usr/include/c++/4.8/bits/stl_iterator.h:805:5: note: template<class _IteratorL, class _IteratorR, class _Container> bool __gnu_cxx::operator==(const __gnu_cxx::__normal_iterator<_IteratorL, _Container>&, const __gnu_cxx::__normal_iterator<_IteratorR, _Container>&)
     operator==(const __normal_iterator<_IteratorL, _Container>& __lhs,
     ^
/usr/include/c++/4.8/bits/stl_iterator.h:805:5: note:   template argument deduction/substitution failed:
a.cc:14:11: note:   ‘std::string {aka std::basic_string<char>}’ is not derived from ‘const __gnu_cxx::__normal_iterator<_IteratorL, _Container>’
   if(s == 'á')

  string s = "áéíóú";
  quitarAcentos(s);
  cout << s;
 //salida ->aaa&#65533;a&#65533;a&#65533;a&#65533;
 

Empiezo a pensar que el problema lo tengo en el ordenador, quizá me falte instalar más codificaciones.

Eso es lo mismo que hacer

int n;
if ( n == 5.55)

esta fuera de rango

El objetivo el transformar unas 15000 urls, quiero quitar acentos de mayúsculas, minúsculas y la ñ, el problema los acentos no caben en un char y por eso no se puede comparar.

if( cadena == 'á')
 

no se puede, y ami me sale que las vocales con acento valen dos char

Necesito quitar acentos de un string, llevo 2 horas y he probado todo lo que se me ocurre, ya dudo hasta si es posible quitarlos con c++.
¿Se os ocurre algo?

No uses return con void

En cuanto a lo de aprender html y css, al año que viene tengo asignaturas de esas características y si que tengo el consentimiento de uso de dichas imágenes. No es viable que guarde en el servidor las imágenes por nº de estas. Cuando hablo de tamaño me refiero a las dimensiones.
Perdonar por las molestias pensaba que sería necesario algo de javascript o php.
es muy simple:

<img src="http://foro.elhacker.net/Themes/converted/selogo.jpg" alt="Logotipo APR2" width="400px" border="5">

Hola, en primer lugar decir que no conozco los lenguajes de programación web. Estoy hacienda una web (todo html) y voy a utilizar imágenes de un tercero alojadas en otro servidor, mi duda es si puedo cambiar el tamaño de estas imágenes.
Si se puede, me pueden indicar el modo.
Un saludo.