How to declare and initialize an array of strings within a class?

Question

I am trying to declare an array of strings representing suits in a deck of cards in my header file and initialize it in my implementation file. I have tried initializer_list as well as tried to initialize it within my constructor, but nothing worked. I finally came across this link Initializing a static const array of const strings in C++, but I don't understand why this works and the previous methods do not.

Why is char used here

static const char * const days[]

instead of string? Why is a pointer being used?

I am confused why I simply cannot declare and initialize the array in my header file as well.

Just use std::array, std::string and an initializer list. — Daniel Kamil Kozar
– Daniel Kamil Kozar, Commented Sep 12, 2014 at 21:32
As mentioned in my op, initializer list doesn't work I get some error stating only "()" is allowed. — Ian004
– Ian004, Commented Sep 12, 2014 at 21:36
possible duplicate of Initializing a static const array of const strings in C++ — nbro
– nbro, Commented Sep 12, 2014 at 21:55

Dimitrios Bouzas · Accepted Answer · 2014-09-12 21:50:40Z

11

First method with C style strings:

struct Foo {
    static char const *arr[];
};

char const *Foo::arr[] = {"ace_hearts", "2_hearts", "3_hearts"};

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Second method with `std::string`:

struct Foo {
    static std::string const arr[];
};

std::string const Foo::arr[] = {"ace_hearts", "2_hearts", "3_hearts"};

LIVE DEMO

Third method with `std::string` and `std::array` and initializer list:

struct Foo {
    static std::array<std::string, 3> const arr;
};

std::array<std::string, 3> const Foo::arr {"ace_hearts", "2_hearts", "3_hearts"};

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answered Sep 12, 2014 at 21:50

Dimitrios Bouzas

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Comments

iWiggins · Accepted Answer · 2014-09-12 22:05:19Z

First: I would recommend not putting string literals into your class to represent suits, it will be a lot easier to make your logic if you use something simple, like an enum or a char.

That aside, the reason why a pointer is being used here rather than using a class such as std::string is because you are storing very simple and exact data (only four possibilities, and you don't need to search it, or split it, etc.) and as such all the extra functionality that std::string includes is unneeded.

A syntax to implement this could be:

static const char* const suits[4];

the const char* is the type of the array (it is an array of const char pointers, which are C-style strings) and the const suits [4] makes it an array of four of them called suits that cannot be changed (is const).

Once the static member is declared in the class, it must be initialized elsewhere and outside the class. For example, in your .h file you would write:

class deck{
public:
static const char* const suits[4];
}

const char* const deck::suits[4]={"hearts","spades","diamonds","clubs"};

It's just how the language syntax works with static members.

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How to declare and initialize an array of strings within a class?

2 Answers 2

First method with C style strings:

Second method with `std::string`:

Third method with `std::string` and `std::array` and initializer list:

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2 Answers 2

First method with C style strings:

Second method with std::string:

Third method with std::string and std::array and initializer list:

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Second method with `std::string`:

Third method with `std::string` and `std::array` and initializer list: