LookUp table Implementation in Qt

[stampede]

Take a look at QHash, you can create a hash table mapping Decimal <-> temperature values, and instead of "if-else" statements simply call:

// _hash contains your Decimal <-> temperature table
if( _hash.contains(str) ){
    temperatureData.append( _hash.value(str) )
}

// _hash contains your Decimal <-> temperature table
if( _hash.contains(str) ){
    temperatureData.append( _hash.value(str) )
}

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----
Edit: looks like Stef was faster

[rex]

Hello thank you for the response. I did look at QMap but could't figure out how i should be doing it.. Din't find any example. Can you pls show a small example.

i will try your method also stampede thank you so much for the example code.

regards

[stampede]

Have you looked at the examples in QMap documentation ?
You just have to store values from your temperature table in such container ( initialize it once somewhere in the program ).

[Stef]

It's not that hard really. First you populate the lookup table with all keys and values. Then if you want to use it you just ask for the key of a specific value.

QMap<QString, QString> lookupTable;
 
    // Populate lookup table
    lookupTable.insert("-40", "289");
    lookupTable.insert("-39", "292");
    lookupTable.insert("-38", "294");
    lookupTable.insert("-37", "296");
    lookupTable.insert("-36", "299");
    lookupTable.insert("-35", "301");    
    // ... And so on
 
    // Use it
    temperaturedata.append(lookupTable.value(str));

QMap<QString, QString> lookupTable;
    
    // Populate lookup table
    lookupTable.insert("-40", "289");
    lookupTable.insert("-39", "292");
    lookupTable.insert("-38", "294");
    lookupTable.insert("-37", "296");
    lookupTable.insert("-36", "299");
    lookupTable.insert("-35", "301");    
    // ... And so on
    
    // Use it
    temperaturedata.append(lookupTable.value(str));

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[rex]

thanks a lot i will do it now.. You made it look so easy.

[wysota]

QHash<int,int> lookUp;
lookup[-40] = 289;
lookup[-39] = 292;
// etc.

QHash<int,int> lookUp;
lookup[-40] = 289;
lookup[-39] = 292;
// etc.

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or using a static C array:

int valueFor(int v) {
  static int lookup[] = { 289, 292, 294, ... };
  return lookup[v+40];
}

int valueFor(int v) {
  static int lookup[] = { 289, 292, 294, ... };
  return lookup[v+40];
}

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