Decompose the polygon with polyline inside

Question

Here is my question:

• I have a polygon shapefile represent the whole country area.
• A polyline shapefile(with a bunch of line boundaries) represent the province boundaries

So, how to decompose the polygon by the polyline inside and get the shapefile file with each province independently?

I'm a new user of QGIS.

I have done the work of combine inner/outer boundaries using MMQGIS->merge layershows like this:

http://i4.tietuku.com/cfcd52e6886109fa.png

But the next step Change this polylines into polygons I can't cope with

• The post about cut the shapefile using digitizing tools didn't work for me
• When I use vector -> Geometry tools -> polyline to polygon, the result shows like this:

http://i4.tietuku.com/7bcda0980879ff24.png

It seems that the inner boundaries had none effect.

Answer 1

I think you're asking the same thing here as in your other question How to combine two polyline shapefile together. See my answer to that question.