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[bind] Surprising behavior
by Christian Henning 16 Apr '07

16 Apr '07

Hi there, I'm sure it's not a bug in bind but I have found a surprising behavior when using it. In my project I have to use some old school c++ classes that use character arrays instead of std::string. The following code displays a difference when using two ways of printing those character arrays. #include <iostream> #include <string> #include <vector> #include <algorithm> #include <functional> #include <boost/bind.hpp> using namespace std; using namespace boost; class A { public: A( string name ) { strncpy( _name, name.c_str(), name.length() + 1 ); } string name() const { return _name; } private: char _name[80]; }; void print( const char* s ) { cout << s << endl; } int main(int argc, char* argv[]) { vector<A> as; as.push_back( A( "A" )); as.push_back( A( "B" )); for_each( as.begin() , as.end() , bind( &print , bind( &std::string::c_str , bind( &A::name, _1 )))); vector<A>::const_iterator it = as.begin(); vector<A>::const_iterator end = as.end(); for( ; it != end; ++it ) { cout << it->name() << endl; } return 0; } The output should be A B A B But instead it's A B The foreach loop doesn't print anything. The problem is when calling the print function the char* points to an empty string. Can somebody please enlightening, here. Thanks, Christian

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[BGL] How to use an array in bundled property?
by Shufei Fan 16 Apr '07

16 Apr '07

I defined an double array inside bundled vertex property, and have trouble finding ways of accessing it. Neither can I find any where in the document an example on it. Your input will be much appreciated! my graph is defined as follows: struct Node { double mode[3]; // this is hard to access }; struct Edge { double nPixels; unsigned short nTh; //no problem access them }; typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::bidirectionalS, Node, Edge> Graph; Graph colGraph; I have no problem with accessing the 'nPixels' in Edge property, boost::property_map<Graph, double Edge::*>::type ew = get(&Edge::nPixels, *colGraph);//edge weight But I am in a great deal of trouble finding ways of accessing 'mode' in Node property. compiler error here: boost::property_map<Graph, double Node::*>::type nm = get(&Node::mode, *colGraph);//node mode error message is : //---------------------------------------------------- c:\...\xxx.cpp(236) : error C2440: 'initializing' : cannot convert from 'boost::property_map<Graph,Property>::type' to 'boost::bundle_property_map<Graph,Descriptor,Bundle,T>' with [ Graph=boost::adjacency_list<boost::vecS,boost::vecS,boost::bidirectionalS,Node, Edge>, Property=double (Node::* )[3] ] and [ Graph=Graph, Descriptor=boost::property_map<Graph,double Node::* >::descriptor, Bundle=Node, T=double ] No constructor could take the source type, or constructor overload resolution was ambiguous //---------------------------------------------------- neither the following works(I added '[3]' in the parameter list): boost::property_map<Graph, double Node::*[3]>::type nm = get(&Node::mode, *colGraph);//node mode This time errors are raised in the 'property.hpp' file, they are: //---------------------------------------------------- c:\Boost\include\boost-1_33_1\boost\pending\property.hpp(40) : error C2825: 'PropertyTag::kind': cannot form a qualified name c:\Boost\include\boost-1_33_1\boost\graph\properties.hpp(198) : see reference to class template instantiation 'boost::property_kind<PropertyTag>' being compiled with [ PropertyTag=double Node::* [3] ] c:\shufei\VCProjects\edison\segm\GA.cpp(236) : see reference to class template instantiation 'boost::property_map<Graph,Property>' being compiled with [ Graph=Graph, Property=double Node::* [3] ] c:\Boost\include\boost-1_33_1\boost\pending\property.hpp(40) : error C2039: 'kind' : is not a member of 'operator``global namespace''' c:\Boost\include\boost-1_33_1\boost\pending\property.hpp(40) : error C2146: syntax error : missing ';' before identifier 'type' c:\Boost\include\boost-1_33_1\boost\pending\property.hpp(40) : error C2955: 'boost::type' : use of class template requires template argument list c:\Boost\include\boost-1_33_1\boost\type.hpp(14) : see declaration of 'boost::type' c:\Boost\include\boost-1_33_1\boost\pending\property.hpp(40) : fatal error C1903: unable to recover from previous error(s); stopping compilation //---------------------------------------------------- thanks, Shufei

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[test] Bug in macros when used with valarray?
by Paul Giaccone 16 Apr '07

16 Apr '07

I have a bug in my program that looks as though it might be in the macros in test. The following line gives me a segmentation fault: BOOST_CHECK_SMALL(var[a][b].first, accuracy); The variable "var" is of type boost::shared_array<std::pair<double, std::valarray<double> > >, for which memory has been allocated as follows (with variable names disguised): const unsigned int num_elements1 = /* some value */; const unsigned int num_elements2 = /* some other value */; const unsigned int num_elements3 = /* another value */; boost::shared_array<boost::shared_array<std::pair<double, std::valarray<double> > > > var_array( new boost::shared_array<std::pair<double, std::valarray<double> > >[num_elements1]); for (unsigned int a = 0; a != num_elements1; ++a) { var[a].reset(new std::pair<double, std::valarray<double> >[num_elements2]); for (b = FirstSolution; b != num_elements2; ++b) { var[a][b].second.resize(num_elements3); } } The variable "accuracy" is of type double. The variable is then passed to a test case: test_suite -> add(BOOST_TEST_CASE(boost::bind(my_test, var))); with this header: void my_test(boost::shared_array<boost::shared_array<std::pair<double, std::valarray<double> > > >& var) Within this test, "var" is passed to another function (by reference) and its contents are set. Outputting the contents shows they have been set OK (using the same array indices, note), but the segmentation fault occurs when the BOOST_CHECK_SMALL macro is used. I am using version 1.33.1 of Boost for gcc 3.2.3. I am linking against -lboost_unit_test_framework-gcc-d-1_33_1 and -lm I'm sure I have used this before without any problems in Linux. The program works perfectly well in Windows using MSVC and Boost version 1.33.1. Are there any other link flags I should be using? Is there something else I have missed? Of course, it is entirely possible that I have an array-out-of-bounds error in my code or something like that, but my diagnostics aren't picking anything like this up, and the Windows version does not report any errors with security checks enabled, and, as I say, outputting the values to std::cout does not cause a segmentation fault. Is it possible that the BOOST_CHECK_* macros don't work with std::valarray in Boost 1.33.1 for gcc 3.2.3? Thanks.

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[mpl] Fix for Visual Studio Compiler Error C1060
by Holcomb, William (Tom ) 16 Apr '07

16 Apr '07

Greetings all, I've seen posts here in the past from those who've had failures compiling (fairly complex) code that uses MPL on Microsoft Visual Studio 2003 and later. On VS 2003, the compiler says that it had an internal error, but on 2005, the error looks like this: File name: fatal error C1060: compiler is out of heap space Happily, Microsoft has published a hotfix for the problem on VS 2005, available at the following link: http://support.microsoft.com/?id=927872 The informal explanation I got is that they had a fixed size internal buffer for holding type names during compilation, and the more complex MPL code--not surprisingly--exceeded that fixed size. I don't know the nature of the fix, though. BTW and FWIW, I never got the error message when compiling in VS 2005 on a 64-bit machine. Hope this helps.

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BoostCon
by Christian Henning 16 Apr '07

16 Apr '07

Hi there, just went over the conference schedule. It looks very interesting but unfortunately I cannot make there. So, my question is if the lectures, speeches, etc. are going to be taped and available to the public, afterwards? I'm thinking of something similar to google education. I'm not sure if that is standard procedure when it comes to conferences. But heh, it's 2007! Thanks, Christian

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Boost graph point of contact
by Stephen Torri 16 Apr '07

16 Apr '07

What group of people or person is a good contact for assistance with the boost graph library? I have not heard back anyone since Friday about a error I am receiving from a test program that I posted. I was wondering if I was going about finding help the wrong way. Stephen

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Regex, no output of greed example.
by Graham Reitz 16 Apr '07

16 Apr '07

There is no output with the following example, when "Note that I'm 21 years old, not" for m[1], and "35" for m[2], is expected. (according to the example): boost::regex reg("(.*)(\\d{2})"); boost::cmatch cm; const char* text = "Note that I'm 21 years old, not 35."; if (boost::regex_search(text, cm, reg)) { if (cm[1].matched) { std::cout << "(.*) matched: " << m[1].str() << std::endl; } if (cm[2].matched) { std::cout << "Found the age: " << m[2].str() << std::endl; } } Output: (.*) matched: Found the age: Expecting: (.*) matched: Note that I'm 21 years old, not Found the age: 35 Any help would be much appreciated. I am new to regular expression and boost::regex. Thanks, Graham

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Boost.Regex with QChar?
by Sebastian Pipping 15 Apr '07

15 Apr '07

It seems to me like Boost.Regex is much more powerful than QRegExp of QT. Can Boost.Regex work with QChar [1] as charT? The text "i.e. either char or wchar_t" on [2] made me unsure of this. Any limitations I should know about? Thanks for your help! Sebastian [1] http://doc.trolltech.com/4.3/qchar.html [2] http://www.boost.org/libs/regex/doc/basic_regex.html

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[dynamic_bitset] beginner question - concatenation/slicing
by Kurt Schwehr 15 Apr '07

15 Apr '07

Hi All, I am new to boost and haven't done much c++ programming in the last couple years, so apologies if this question is obvious. I'm looking at dynamic_bitset to build a translator between the bits and NMEA string packaging for Maritime AIS. Basically this is each character in a string represents 6 bits of data. I'd like to make two lookup tables that let me go back and forth quickly between bitsets and the NMEA ASCII. My dynamic_bitset questions are: * how can I best concatenate multiple dynamic_bitsets? For example: lookupbits['a']+lookupbits['1']+lookupbits['g'] would return a dynamic_bitset of 18 bits. I'm looking for some sort of join operation and append does not seem to do what I want. * How can I best slice the results? If I know that, for example, and unsigned integer is at bits 11-14, is there way to do quickly get a dynamic_bitset of those bits? I've got all this working in pure python, but it is way to slow ( http://vislab-ccom.unh.edu/~schwehr/software/noaadata/ in the ais package). Any suggestions would be greatly appreciated. Thanks! -kurt http://schwehr.org

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BGL: need help with connected_components and boost::setS
by Maarten Nieber 15 Apr '07

15 Apr '07

Hi all, can anyone help me with the compile error I get when compiling the following code? I'm using the MSVC 7.1 compiler (but it is not an internal compiler error). The error occurs in the last line. Your help is appreciated! With kind regards Maarten #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/connected_components.hpp> // Identifies the "component number" property struct component_t { enum { num = 4564 }; typedef boost::vertex_property_tag kind; }; void Test() { using namespace boost; // The "component number" property is an integer for each vertex typedef boost::property<component_t, int> VertexComponentProperty; // A graph with list storage and the "component number" property. typedef boost::adjacency_list < boost::setS, boost::setS, boost::undirectedS, VertexComponentProperty > Graph; // The property map typedef boost::property_map<Graph, component_t>::type ComponentPropertyMap; Graph g; ComponentPropertyMap vertexToComponent = boost::get(component_t(), g); // THIS LINE DOES NOT COMPILE. No problem if boost::vecS is used instead of boost::setS in the Graph typedef! connected_components(g, vertexToComponent); } __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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