CODEWITHSUNDEEP
c++
user1001776
user1001776

Reputation: 197

How do I add an enumeration type to reference an array

My guess is. However all the example I see create an instance of item_type say item_type_instance. However my case is more simpler...I want something descriptive for my array not just using 0 and 1.

enum item_type {weight, cost};

and then substitute weight and cost for 0 and 1.

void algo(int cost_low,int cost_high,int throw_weight, int item_id)
  {
  int quantity,remainder;
  quantity=throw_weight/item_matrix[item_id][0];
  remainder=throw_weight%item_matrix[item_id][0];
  if(remainder==0)
    {
    cost_low=(quantity-1)*item_matrix[item_id][1];
    cost_high=quantity*item_matrix[item_id][1];
    throw_weight-=(quantity-1)*item_matrix[item_id][0];
    }
  else
    {
    cost_low=quantity*item_matrix[item_id][1];
    cost_high=(quantity+1)*item_matrix[item_id][1];  
    throw_weight-=quantity*item_matrix[item_id][0];
    }
  }

Upvotes: 0

Views: 71

Answers (3)

xtofl
xtofl

Reputation: 41519

Of course you could do that; but wouldn't you rather represent the items in the item_matrix by something more meaningful than an array?

struct Item {
  int weight;
  int cost;
};

This may render your algorithm more readable:

void algo(int cost_low,int cost_high,int throw_weight, int item_id)
  {
  int quantity,remainder;
  Item& item = item_matrix[item_id];
  quantity=throw_weight/item.weight;
  remainder=throw_weight%item.weight;
  if(remainder==0)
    {
    cost_low=(quantity-1)*item.cost;
    cost_high=quantity*item.cost;
    throw_weight-=(quantity-1)*item.weight;
    }
  else
    {
    cost_low=quantity*item.cost;
    cost_high=(quantity+1)*item.cost;  
    throw_weight-=quantity*item.cost;
    }
  }

It may be possible to refactor even further, and delegating the calculation to the Item, too.

-- EDIT I couldn't resist... It is possible to delegate to the Item itself, getting rid of all the item.xxx notations.

struct Item {
   int weight;
   int cost;

   void algo( int& cost_low, int& cost_high, int& throw_weight ) {
      int quantity = throw_weight / weight;
      int remainder = throw_weight % weight;

      cost_low=(quantity-1)*cost;
      cost_high=quantity*cost;
      throw_weight -= (quantity-1)*weight;

      if( remainder != 0 ) {
         cost_low += cost;
         cost_high += cost;
         throw_weight += weight;
      }
   }
};

Usage:

item_matrix[item_id].algo( cost_low, cost_high, throw_weight );

Upvotes: 3

Sarfaraz Nawaz
Sarfaraz Nawaz

Reputation: 361702

If I understand your question correctly then I think you want to use enum as index to the array. If so, then you can do that:

quantity=throw_weight/item_matrix[item_id][weight]; //weight <=> 0
cost_low=(quantity-1)*item_matrix[item_id][cost];   //cost   <=> 1

The value of weight and cost are 0 and 1 respectively, so the above code is perfectly fine. If the value for enumeration is not provided, then it starts with 0 and increments 1 with each subsequent enum label.

Upvotes: 0

K-ballo
K-ballo

Reputation: 81389

Simply define the enumerators to be 0 and 1:

enum item_type
{
    weight = 0
  , cost = 1
};

The standard conversion from enum to int will allow you to use enumerations to index an array.

Upvotes: 1

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