Question

I cant get enum this to work properly on Windows. While compiling on linux it returns expected value, but on windows it returns some random number.

typedef enum wezly {
    elektrownie1,
    konwencjonalne1,
    niekonwencjonalne1,
    weglowa1,
    jadrowa1,
    sloneczna1,
    wiatrowa1,
    geotermiczna1,
    gazowa1,
    wodna1,
    maremotoryczna1,
    maretermiczna1
};

wezly wybor_wezla(string opcja)
{
    string bb;
    bb = opcja;

    if ((bb.compare("[elektrownie]")==0)||(bb.compare("[ELEKTROWNIE]")==0))
        return elektrownie1;
    else if ((bb.compare("[konwencjonalne]")==0)||(bb.compare("[KONWENCJONALNE]")==0))
        return konwencjonalne1;
    else if ((bb.compare("[gazowa]")==0)||(bb.compare("[GAZOWA]")==0))
        return gazowa1;
    else if ((bb.compare("[wodna]")==0)||(bb.compare("[WODNA]")==0))
        return wodna1;
    // (and so on...)
}

int main()
{

    cout << wybor_wezla("[gazowa]");
}

When on linux i get 7, on windows its some random number….

Why can that be ?

Answer 1

Your code is missing a final else clause:

wezly wybor_wezla(string opcja)
{
    if(...)
        return ...;
    else if(...)
        return ...;
    else if(...)
        return ...;
    // No final else!
}

When none of the if clauses are true, it falls off the end of the function without returning a value, which is Undefined Behavior. In this case, it’s returning a garbage value, but worse stuff could happen.

Your first action should be to add a final else clause. This can return a default value, an error code, throw an exception, abort(), etc., but it cannot do nothing. If you know the value has to be one of a limited set of things, you could change the final else if into just an else and assume that if it’s not the first N-1 things, it’s the Nth thing.

Once you’ve done that, you need to figure out why your data isn’t falling into one of the expected cases and fix that.