对c ++类的怀疑

Question

I'm doing a simple c++ project about a card game and i'm using the following class to represent cards:

class card{
public:
    int suit;
    int value;
    bool check;//i need it for various things
    card(): suit(0), value(0), check(false) {}
    void set_check(bool a){check=a;}
    void card_name(); //given a card name, it generate the suit and value of the card
    string suit_name(int); //print card suit name
    string value_name(int);//print card value name
};

Now, it's the first time i use classes so i have some doubts:

1) The first time i used the class card it didn't have any default constructor, it was like this:

class card{
public:
    int suit;
    int value;
    void card_name();
    string suit_name(int);
    string value_name(int);
};

whenever i needed to initialize a card i did something like card a={0,0}; . With the new class the constructor initialize the object, but in some functions i use the syntax card a={suit,value}; to assign numbers to members suit and value . It worked before, but with the constructor it shows the error error: no match for 'operator=' (operand types are 'card' and '<brace-enclosed initializer list>') or also error: could not convert '{0, 0}' from '<brace-enclosed initializer list>' to 'card'

I know how to avoid this (i'll add a set_values member function) but i was just curious about what exactly make this happen(is it because {...} is an initializer and causes a double initialization?).

2) Is there a different way, beside using a constructor, to set a member of a class to a default value (ie i need check to be initialized as false , unless i explicitly change it through card::set_check(bool) )? If i defined the class like this

class card{
public:
    int suit;
    int value; 
    bool check=false;
    void set_check(bool a){check=a;}
    void card_name();
    string suit_name(int);
    string value_name(int);
};

would it work? And, assuming the class as above, could i initialize an object simply by card a={0,0} without specifying check value?

3) Last and also the least important, so don't mind that much. I was wondering if there's a way to initialize and assign values to elements in an array of card without using a specific constructor for arrays. I mean, assume class is

class card{
    int suit;
    int value;
    bool check;
    card(int a, int b, bool c=false): suit(a), value(b), check(c) {}
   //other functions
};

When i was using the class card without constructor, i declared the following array card array[5]={{1,1},{2,3},{3,5}, ...} , but it gives me problem with the new constructor for point 1 above.

I saw on another forum that it was allowed to do something like this

card array[5]={card(1,1), card(2,3), card(3,5), ...}

ie initializing an array with brace-enclosed initializer and calling the constructor inside the braces. Is this really allowed? Is there another way to do something like this using constructors?

Answer 1

Re: 1

card a={suit,value};

doesn't work since you have an explicitly defined default constructor. You can use another constructor to make it work.

card(int s, int v): suit(s), value(v), check(false) {}

Re: 2

Yes,

bool check=false;

is a good way to initialize check to false .

Re: 3

If you define the second constructor, you should be able to use:

card array[5]={{1,1},{2,3},{3,5}, ...};