how to assign an array as another array within a class function

Question

this is basically what I am trying to do:

class Player
{
public:
    void setInventory(string inventory[]) { this->inventory = inventory; }
private:
    string inventory[4];
};

normally I would use strncpy(); but sadly using the parameter inventory[] as the source does not work because it isn't a const char *. I want to keep this as an in class function if possible in one or two lines. I just want to know if there is a short way of doing this rather than creating a function outside of the class for it. Thanks

I recommend you learn about std::array. Or about std::copy. — Some programmer dude
– Some programmer dude, Commented Mar 6, 2016 at 3:02

Daniel Jour · Accepted Answer · 2016-03-06 03:15:27Z

2

There's std::copy if you want copies of the array elements or std::move if you're allowed to move from them.

Example:

class Player
{
public:
    void setInventory(std::string inventory[]) {
        std::copy(inventory, inventory + 4, this->inventory);
    }
private:
    std::string inventory[4];
};

Note that you should make sure that your "array parameter" (it's a pointer, actually) should've (at least) the required 4 elements. If possible it's better to encode the size into the type, for example using std::array.

struct Player {
  void setInventory(std::array<std::string, 4> i) {
    inventory = i;
  }
  std::array<std::string, 4> inventory;
};

This works because std::array implements the assignment operator operator=.

edited Mar 6, 2016 at 3:15

answered Mar 6, 2016 at 3:03

Daniel Jour

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Comments

Aiken Drum · Accepted Answer · 2016-03-06 03:29:04Z

0

You should really make your inventory storage into a type or class itself so you can treat it uniformly and clearly. That would automatically get you copy/move operations (assuming a recent standards-compliant compiler) to keep the handling clear:

typedef std::array<std::string, 4> Inventory;

class Player
{
public:
    void setInventory(Inventory &&inventory) {
        this->inventory = inventory;
    }
private:
    Inventory inventory;
};

Doing it this way also allows you to expand & enhance Inventory itself in the future with zero or minimal refactoring of code that handles it from the outside.

answered Mar 6, 2016 at 3:29

Aiken Drum

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Comments

songyuanyao · Accepted Answer · 2016-03-06 03:32:38Z

0

You won't use stdncpy(), inventory is an array of std::string, not char.

You can write a simple loop to do this,

void setInventory(string inventory[]) {
    for (int i = 0; i < 4; i++) 
        this->inventory[i] = inventory[i];
}

but the most simple way is to use std::array.

class Player
{
public:
    void setInventory(const std::array<std::string, 4>& inventory) { this->inventory = inventory; }
private:
    std::array<std::string, 4> inventory;
};

edited Mar 6, 2016 at 3:32

answered Mar 6, 2016 at 3:06

songyuanyao

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