Concatenating fields in field calculator of QGIS?

In recent QGIS versions (>= 2.6), + works for string concatenation

tostring(hectares) + ' ha'

Previously, the only concatenation operator was: ||

tostring(hectares) || ' ha'

Right-Click on the layer -> Properties -> Labels Then you can use the following function "concat(string1, string2,... ) :

I hope it will be usefull.

You can also append text or put spaces between using alternate quotations:

 "Streetnum" || ' ' || "Streetname"