Retriving latitude & longitiude.

i followed the below example link

[url]http://www.developer.nokia.com/Community/Wiki/Retrieving_location_information_using_Symbian_C%2B%2B[/url] to retrieve the latitude & longitude of the cell.

as per the example i implemented the MPositionObserver ABCclass to CUnregisterview class. The functions

virtual void PositionUpdatedL(TPositionInfoBase& aPosInfo) = 0;
virtual TInt ErrorL(TInt aError) = 0;

was overridden in CUnregisterview class as : -

void CUnRegisterView ::PositionUpdatedL(TPositionInfoBase& aPosInfo)
{
if (aPosInfo.PositionClassType() & EPositionInfoClass)
{
// Cast the TPositionInfoBase object to TPositionInfo
TPositionInfo* posInfo = static_cast<TPositionInfo*>(&aPosInfo);

// Get position
TPosition position;
posInfo->GetPosition(position);

// Convert positions to the descriptors
TBuf<KDegreeLength> latitudeDegr;
GetDegreesString(position.Latitude(), latitudeDegr);

// Convert positions to the descriptors
TBuf<KDegreeLength> longitudeDegr;
GetDegreesString(position.Longitude(), longitudeDegr);

}

}



GetDegreesString was defined as:----



void CUnRegisterView::GetDegreesString(
const TReal64& aDegrees,TBuf<KDegreeLength>& aDegreesString) const
{
const TReal KSecondsInMinute = 60.0;
const TInt KNumWidth = 3;

// If the aDegree is a proper number
if ( !Math::IsNaN(aDegrees) )
{
// Integer part of the degrees
TInt intDegrees = static_cast<TInt>(aDegrees);

// Positive float of the degrees
TReal64 realDegrees = aDegrees;

// Convert to positive values
if ( intDegrees < 0 )
{
intDegrees = -intDegrees;
realDegrees = -realDegrees;
}

// Minutes
TReal64 realMinutes = (realDegrees - intDegrees) * KSecondsInMinute;

// Integer part of the minutes
TInt intMinutes = static_cast<TInt>(realMinutes);

// Seconds
TReal64 realSeconds = (realMinutes - intMinutes) * KSecondsInMinute;
TInt intSeconds = static_cast<TInt>((realMinutes - intMinutes) * KSecondsInMinute);

// Check the sign of the result
if ( aDegrees >= 0 )
{
aDegreesString.Append(KDelimPlus);
}
else
{
aDegreesString.Append(KDelimMinus);
}

// Add the degrees
TInt64 value = intDegrees;
aDegreesString.AppendNum(value);

// Add the separator
aDegreesString.Append(KDelimDegree);

// Add the minutes
value = intMinutes;
aDegreesString.AppendNum(value);

// Add the separator
aDegreesString.Append(KApostrophe);

// Add the seconds
value = intSeconds;
aDegreesString.AppendNum(value);

// Add the separator
aDegreesString.Append(KDelimQuot);

// Add the separator
aDegreesString.Append(KDelimDot);

// Get six last digits
realSeconds -= intSeconds;
realSeconds *= 1000;

// Add the seconds
aDegreesString.AppendNumFixedWidth(static_cast<TInt>(realSeconds),
EDecimal, KNumWidth);
}
}




IN side handle command in unregisterview under switch case i called ...


case ELocation:
{

iSearchLocation = CLocation::NewL(1000000*10,*this); //This is the pointer of CLocation* iSearchLocation;
TPositionInfoBase* pos = iSearchLocation->CurrentPosition();
PositionUpdatedL(*pos);
}
break;

PositionUpdatedL(*pos); is defined in upper section.


I am getting error of ekern exe3 in the line
TPositionInfoBase* pos = iSearchLocation->CurrentPosition();


Please help..
Thanks in advance.

instead of defining
[B]virtual void PositionUpdatedL(TPositionInfoBase& aPosInfo) = 0;
virtual TInt ErrorL(TInt aError) = 0;[B]

define:
void PositionUpdatedL(TPositionInfoBase& aPosInfo);
TInt ErrorL(TInt aError);

Dear All,

I was trying the link [url]http://www.developer.nokia.com/Community/Wiki/Retrieving_location_information_using_Symbian_C%2B%2B#See_also[/url] to retrieve the Location information.

Ok,

As per this i put the .cpp & .h file in that. After that i have a interface class ...

CGpsLocationEngine;

lass CGpsLocationEngine : public CBase, public MPositionObserver
{

public:

static CGpsLocationEngine* NewL();

CGpsLocationEngine();

void ConstructL();

virtual ~CGpsLocationEngine();

void PositionUpdatedL(TPositionInfoBase& aPosInfo);
void ErrorL(TInt aError);
TPositionInfoBase* GetPositionInfoBase();
void GetDegreesString( const TReal64& aDegrees,TBuf<19>& aDegreesString) const;
void ProcessPositionInfoL(const TPositionInfo& aPositionInfo );
TDesC& LAT_LONG_String();
void GetPosition();

private: //methods

CLocation* iLocation;
};


After that in .cpp file i did the overriding of the function:-

void PositionUpdatedL(TPositionInfoBase& aPosInfo);
void ErrorL(TInt aError);

in the manner that:->

void CGpsLocationEngine::PositionUpdatedL(TPositionInfoBase& pos)
{

if (pos.PositionClassType() & EPositionInfoClass)
{
// Cast the TPositionInfoBase object to TPositionInfo
TPositionInfo* posinfo = static_cast<TPositionInfo*>(&pos);
// Process the position information
ProcessPositionInfoL( *posinfo );
}
}


void CGpsLocationEngine::ProcessPositionInfoL(
const TPositionInfo& aPositionInfo )
{
// Get basic position data
TPosition position;
aPositionInfo.GetPosition(position);

TBuf<KDegreeLength> latitudeDegr;
GetDegreesString(position.Latitude(), latitudeDegr);

TBuf<KDegreeLength> longitudeDegr;
GetDegreesString(position.Longitude(), longitudeDegr);
}

void CGpsLocationEngine::GetDegreesString(
const TReal64& aDegrees,TBuf<19>& aDegreesString) const
{
const TReal KSecondsInMinute = 60.0;
const TInt KNumWidth = 3;

// If the aDegree is a proper number
if ( !Math::IsNaN(aDegrees) )
{
// Integer part of the degrees
TInt intDegrees = static_cast<TInt>(aDegrees);

// Positive float of the degrees
TReal64 realDegrees = aDegrees;

// Convert to positive values
if ( intDegrees < 0 )
{
intDegrees = -intDegrees;
realDegrees = -realDegrees;
}

// Minutes
TReal64 realMinutes = (realDegrees - intDegrees) * KSecondsInMinute;

// Integer part of the minutes
TInt intMinutes = static_cast<TInt>(realMinutes);

// Seconds
TReal64 realSeconds = (realMinutes - intMinutes) * KSecondsInMinute;
TInt intSeconds = static_cast<TInt>((realMinutes - intMinutes) * KSecondsInMinute);

// Check the sign of the result
if ( aDegrees >= 0 )
{
aDegreesString.Append(KDelimPlus);
}
else
{
aDegreesString.Append(KDelimMinus);
}

// Add the degrees
TInt64 value = intDegrees;
aDegreesString.AppendNum(value);

// Add the separator
aDegreesString.Append(KDelimDegree);

// Add the minutes
value = intMinutes;
aDegreesString.AppendNum(value);

// Add the separator
aDegreesString.Append(KApostrophe);

// Add the seconds
value = intSeconds;
aDegreesString.AppendNum(value);

// Add the separator
aDegreesString.Append(KDelimQuot);

// Add the separator
aDegreesString.Append(KDelimDot);

// Get six last digits
realSeconds -= intSeconds;
realSeconds *= 1000;

// Add the seconds
aDegreesString.AppendNumFixedWidth(static_cast<TInt>(realSeconds),
EDecimal, KNumWidth);
}
}

I am unable to understand that i have to call

// Class that use CLocation have to implement
// MPositionObserver interface. Via MPositionObserver are position
// and error messages send.
iSearchLocation = CLocation::NewL(1000000*10,*this); //It will be in ConstructL

// Get current position
TPositionInfoBase* pos = iSearchLocation->CurrentPosition();

Now suppose from a screen from a command Location i just want to retrieve the location.
In that Case i will call the function
TPositionInfoBase* pos = iSearchLocation->CurrentPosition();
"or"
PositionUpdatedL(TPositionInfoBase& pos)

How could i implement the same.

[B]Please Guide if I am wrong at any points. [/B]

best idea would be to have callback implemented in ProcessPositionInfoL() which would tell you when it has position updated.

[QUOTE=symbianyucca;906085]instead of defining
[B]virtual void PositionUpdatedL(TPositionInfoBase& aPosInfo) = 0;
virtual TInt ErrorL(TInt aError) = 0;[B]

define:
void PositionUpdatedL(TPositionInfoBase& aPosInfo);
TInt ErrorL(TInt aError);[/QUOTE]



Yes I did the same in the interface class.

[QUOTE=akki123;908021]Yes I did the same in the interface class.[/QUOTE]

And what was the difference ?

Here i am able to build & debug it for emulator. But when i am debugging it for GCCE compiler it is giving an error

undefined reference to `vtable for CGpsLocationEngine'

The interface ("class MPositionObserver{...}") has to remain the abstract virtual thing.
When you inherit the methods in your own class, the abstract (=0) has to be removed. virtual does not matter, there is a C++ saying for this: "Once virtual, always virtual", so this property is inherited automatically.
Note that Wiki articles are created by random people, so it is always a good idea to check official examples too, given that they exist. In this case they do, the SDK-s have Location/PositionXY examples, and there are a couple here in the Code Examples section, [url]https://www.developer.nokia.com/Develop/Featured_Technologies/Symbian_C++/Code_examples/Location.xhtml[/url]