lookup table

[georgie]

what do you think is an efficient way of implementing a lookup table in c++

i'd use a vector or some other safe container, except calling push_back 400 times seems ridiculous.....

and i've currently got it as a cstyle array, but that is giving me weirrrrrrrrd results....

class LookupTable: public QWidget
{
 public:
  LookupTable();
  int lookupElectrodeNumber(int i);
 private:
  int base_filter[21][13];
  int id_filter[13][21]; 
  int number_to_filter [100];
};
#endif//LOOKUP_TABLE_

class LookupTable: public QWidget
{
 public:
  LookupTable();
  int lookupElectrodeNumber(int i);
 private:
  int base_filter[21][13];
  int id_filter[13][21]; 
  int number_to_filter [100];
};
#endif//LOOKUP_TABLE_

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LookupTable::LookupTable()
{
 
  int::number_to_filter[] = { blah blah blah....a heck of a lot of numbers};
 
}
 
int LookupTable::lookupElectrodeNumber(int i)
{
  return number_to_filter[i];
}

LookupTable::LookupTable()
{
  
  int::number_to_filter[] = { blah blah blah....a heck of a lot of numbers};
      
}

int LookupTable::lookupElectrodeNumber(int i)
{
  return number_to_filter[i];
}

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seems simple....but gives wacky stuff....

[zlatko]

First of all cut this code

int base_filter[21][13];
int id_filter[13][21];

int base_filter[21][13];
int id_filter[13][21];

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if its not actual

Then show how do you init your vector,how do you call method lookupElectrodeNumber and what his retturn ?

[jacek]

LookupTable::LookupTable()
{

int::number_to_filter[] = { blah blah blah....a heck of a lot of numbers};

}

You create a local variable, instead of initializing the number_to_filter member variable.

Does the contents of base_filter, id_filter and number_to_filter change?

[georgie]

no....it's pre defined (for a weird numbering system of nodes which goes in a quasi hexagonal fashion) and won't change

[ball]

How about using QMap class?

[wysota]

How about a global static predefined array?

static int base_filter[21][13] = { {1...21}, {22...42}, ...};

static int base_filter[21][13] = { {1...21}, {22...42}, ...};

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[jacek]

How about a global static predefined array?

I would do it this way:

namespace
{
   const int base_filter[21][13] = { { 1, ..., 21 }, { 22, ..., 42 }, ... };
}

namespace
{
   const int base_filter[21][13] = { { 1, ..., 21 }, { 22, ..., 42 }, ... };
}

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