Question about enum

[XanaRaquel]

Hi all!

Ok, so let's say I have this enum:

  enum letters {A, B, C, D, E, F};
  letters l;

and I ask the user to choose a letter and he types D.
I know D has the value 3 but how can I get the number?

something like:

int x = D; // x equals D 

but where's D I want the letter the user chose and x equals to the value corresponding to that letter in the enum.

Or maybe enums aren't the best for this situation?

[dmpaul26]

using enums would be fine. The code you presented would make the value stored in x a 3. Which is what it sounds like you want.

[XanaRaquel]

dmpaul26, not really. here's a more complete example of what I really want:

enum letters {A, DD, CON, D, HELP, FIRE}; // just an example
int x;
string s;

cout << "Choose a code!";
cin >> s  //user typed D

x = .... // now what? 

I can't put x = stoi(s) because that would just convert the string into a int. I wanted to check if the s is in the enum and return the value associated to it (in this case, 3).

[JLBorges]

#include <iostream>
#include <cctype>

enum letter { A, B, C, D, E, INVALID = -1 };

std::istream& operator>> ( std::istream& stm, letter& opt )
{
    char c ;
    stm >> c ;
    switch( std::toupper(c) )
    {
        case 'A' : opt = A ; break ;
        case 'B' : opt = B ; break ;
        case 'C' : opt = C ; break ;
        case 'D' : opt = D ; break ;
        case 'E' : opt = E ; break ;
        default : opt = INVALID ;
    }

    return stm ;
}

int main()
{
    letter choice ;
    std::cout << "choice [A-E]? " ;
    std::cin >> choice ;
    // ...
}

#include <iostream>
#include <string>

enum colour_t { BLACK, RED, GREEN, BLUE, WHITE, INVALID = -1 };

std::istream& operator>> ( std::istream& stm, colour_t& clr )
{
    std::string str ;
    stm >> str ;
    if( str == "BLACK" ) clr = BLACK ;
    else if( str == "RED" ) clr = RED ;
    else if( str == "GREEN" ) clr = GREEN ;
    else if( str == "BLUE" ) clr = BLUE ;
    else if( str == "WHITE" ) clr = WHITE ;
    else clr = INVALID ;

    return stm ;
}

int main()
{
    colour_t clr ;
    std::cout << "colour [BLACK, RED, GREEN, BLUE, WHITE]? " ;
    std::cin >> clr ;
}