How do I bring the Z value to attribute table?

Question

I have a shapefile exported from a hydraulics software that I use. The file is exported as polylines. I convert it to a point layer using the "Extract Nodes" function. The remaining piece of information I need is the elevation (z value) of each point. I know they exist because I can see them, in the Vertex editor and the wkt_geom column when I copy paste to Excel. I see the "z()" function but can't figure out the appropriate syntax.

I tried this: z(geom_from_wkt( [shapefile_name]))

Is there a function, or a work-around, similar to the $x and $y functions to extract the z value from the geometry and display it in the attribute table?

I am talking about a point shapefile, and using QGIS 2.18.

Answer 1

Try the following expression :

z($geometry)

The help says "z(geom)" geom being a point geometry ... so i don't think there's any benefit trying to play with wkt expressions ....