Re: [Boost-users] Trouble converting johnson_all_pairs to use file IO.

David E. Konerding DSD staff wrote:

Hi folks,

I'm trying to convert the Boost Graph Library example from a graph built in the code, to one that usses the adjacency_list_io supporto load the graph from a file. I was able to convert the dijkstra example this way, and had no problems.

I'm getting a weird error when I disable GRAPH_CODE (this example is very close to the true example in the boost source distribution):

test.cpp: In function `int main(int, char**)': test.cpp:44: no matching function for call to `johnson_all_pairs_shortest_paths (main(int, char**)::Graph&, int[V][V], boost::bgl_named_params)'

Sorry to follow up on my own post, but I figured it out on my own :-) Inspecting the signature for the missing reference, I pondered the "int[V][V]" (the distance map parameter) and finally realized that it was having trouble with the array declaration syntax when the value was based on a non-compile time value (the number of vertices in the graph wasn't a constant at compile time in my failing case). I'm sure this is all well defined in the C++ rules, and when I built the distance map array by hand using int **, it appeared to work. Thanks, Dave