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  1. #1
    Registered User
    Join Date
    Nov 2010

    what's "a null update"?

    in the help file:

    QGeoPositionInfo QGeoPositionInfoSource::lastKnownPosition ( bool fromSatellitePositioningMethodsOnly = false ) const [pure virtual]

    Returns an update containing the last known position, or a null update if none is available.

    If fromSatellitePositioningMethodsOnly is true, this returns the last known position received from a satellite positioning method; if none is available, a null update is returned.

    my question is how to determine the return value is availbale. what's "a null update"? sample code is prefered.

    Thank you!

  2. #2
    Regular Contributor
    Join Date
    Oct 2008
    Oslo, Norway

    Re: what's "a null update"?


    If no last known position is available, it'll return an instance of QGeoPositionInfo that was created using a default constructor, i.e. with none of the attributes set. In this case, QGeoPositionInfo::isValid() will return false.

  3. #3
    Registered User
    Join Date
    Nov 2010

    Re: what's "a null update"?

    I see.
    Thank you!

    I have another question, please refer to the position getted by QGeoPositionInfoSource not accurate .

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