Combine Arrangements with Enum [duplicate]

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Combine Arrangements with Enum [duplicate]

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#1 by (3 votes)
#2 by (3 votes)

1

I have an enumeration with the months, something like that

enum Meses {
 Enero,
 Febrero,
 [...],
 Diciembre };

I have an arrangement, where I store entire data. Now, what I need to do is something like

for (int i = 0; i < n; i++) // Donde n es el numero de datos en el arreglo
{
  if (Arreglo[i] >= 12) // Mayor que 12, ya que diciembre tendrá valor 11
     cout << "Error";
  else
     cout << Meses[Arreglo[i]] << endl;
}

In case you do not understand, what I want to do is that given the entire value in the array, show the corresponding data in the enumeration Meses .

Can something like that be done?

c++ array enum

asked by Byte 21.10.2018 в 19:55

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2 answers

3

There are no standard mechanisms to convert an enumerated one into a string ... however it is possible to achieve that effect.

The first thing is to create a new file, for example Meses.inc with a content such that:

MES(Enero)
MES(Febrero)
MES(Marzo)
MES(Abril)
MES(Mayo)
MES(Junio)
MES(Julio)
MES(Agosto)
MES(Septiembre)
MES(Octubre)
MES(Noviembre)
MES(Diciembre)

This file will be the base that will allow us to automatically generate all the code we need. We just need to redefine the macro MES to generate the code we need at each moment. So, to fill in the list:

enum Meses
{
  #define MES(x) x,
  #include "Meses.inc"
  #undef MES
};

With this we get the preprocessor to generate a code such that:

enum Meses
{
  Enero,
  Febrero,
  Marzo,
  // ...
};

While to have a function that allows us to convert the values of the enumerated in chain:

std::string MesToString(Meses mes)
{
  switch(mes)
  {
    #define MES(x) case x: return #x;
    #include "Meses.inc"
    #undef MES
  }

  return "";
}

The possibilities are endless and, best of all, in the file meses.inc we can add additional information ... for example text in different languages:

MES(Enero,January)
MES(Febrero,February)
MES(Marzo,March)
MES(Abril,April)
MES(Mayo,May)
MES(Junio,June)
MES(Julio,July)
MES(Agosto,August)
MES(Septiembre,September)
MES(Octubre,October)
MES(Noviembre,November)
MES(Diciembre,December)

Now, to generate the enumerated one we are only interested in the first parameter:

enum Meses
{
  #define MES(x,y) x,
  #include "Meses.inc"
  #undef MES
};

And to convert to string :

std::string MesToString(Meses mes,bool ingles)
{
  switch(mes)
  {
    #define MES(x,y) case x: return ingles ? #y : #x;
    #include "Meses.inc"
    #undef MES
  }

  return "";
}

The bad part of using this mechanism is that the IDEs, will not be able to give us information about the values of the enumerated ( intellisense ), but in return we have a very powerful and versatile mechanism that Avoid writing a good number of lines of code. The compilation time will also be noticeably longer.

answered by 21.10.2018 в 22:01

switch with cases of many possibilities how can I go through the next json

score 3 · Accepted Answer

Not directly. The simplest solution would be to have an array of strings with the names of the months:

char *NombresMeses[] = {
     "Enero", "Febrero", ...
};

and you'll use indexes inside that array to get the names:

for (int i = 0; i < n; i++) // Donde n es el numero de datos en el arreglo
{
  if (Arreglo[i] >= 12) // Mayor que 12, ya que diciembre tendrá valor 11
     cout << "Error";
  else
     cout << NombresMeses[Arreglo[i]] << endl;
}

The Enum do not really need it for this, but it may be convenient to keep it in case you want to compare numbers with months. There will always be more readable something like:

if (Arreglo[i] == Enero) ...

in front of:

if (Arreglo[i] == 0) ...