Building error with QgsVectorFileWriter

Question

I am working with qgis api c++ 2.8.2, in c++/QT 4.5 I try to save my List of QgsField but I have the error message : no matching for call to 'QgsVectorFileWriter' I took the sample from here :

http://hub.qgis.org/issues/7223

Here is my code in C++

QList <QgsField> lMyAttribField;
QgsVectorFileWriter * writer;
writer = QgsVectorFileWriter("/tmp/myshapes.shp", "CP1250", lMyAttribField, QGis::WKBPoint, "0", "ESRI Shapefile");

I have the same eror if I delete the * in the declaration of writer

I don't understand what's i forget ?

Answer 1

If you review the API (http://qgis.org/api/classQgsVectorFileWriter.html) for QgsVectorFileWriter, the constructor looks like:

QgsVectorFileWriter::QgsVectorFileWriter    (   const QString &     vectorFileName,
        const QString &     fileEncoding,
        const QgsFields &   fields,
        QGis::WkbType   geometryType,
        const QgsCoordinateReferenceSystem *    srs,
        const QString &     driverName = "ESRI Shapefile",
        const QStringList &     datasourceOptions = QStringList(),
        const QStringList &     layerOptions = QStringList(),
        QString *   newFilename = 0,
        SymbologyExport     symbologyExport = NoSymbology 
    )   

The likely problem is that you are passing a string ("0") instead of a pointer to QgsCoordinateReferenceSystem for the srs argument. In Nathan's follow-up he passed in null (note 0, not "0")

Answer 2

Here is the code without error

QgsVectorFileWriter * writer;
writer = new QgsVectorFileWriter("/tmp/myshapes.shp",
                                    "CP1250",
                                    MyQgsFields,
                                    QGis::WKBPoint,
                                    mpMapCanvas->mQgsCoordinate,
                                    "ESRI Shapefile");

where MyQgsFields is a QgsFields, and mpMapCanvas->mQgsCoordinate is a QgsCoordinateRefenceSystem

it works when i launch my application and add a tracks a file was created in /tmp . i can open it in QGIS without error but at this step it contains nothing , no data