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  • How to tell what optimizations bjam is using to build boost

    - by Steve
    I'm building the boost libraries with bjam for both the intel compiler and vs2008, and I can't tell what optimizations are being passed to the compiler from bjam. For one of the compiler's gcc, I can see some optimizations in one of the bjam files, but I can't find the optimization flags for the compilers I care about. So, my questions are - Does anyone know where the default optimization flags are located? If they're declared within bjam, does anyone know how I can override them?

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  • Boost BGL thread safety

    - by Budzoli
    Hi! I'd like multiple threads to use the dijkstra_shortest_paths and astar_search functions of the BGL, and then read the property maps of the result vertices and edges. I'm wondering wether I should use mutexes to ensure thread-safety. So here are my questions: 1., Are the dijkstra_shortest_paths and astar_search functions of the Boost.Graph thread safe? 2., If I only try to read the property maps of the graph from multiple threads, do I need to worry about thread safety?

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  • Boost.Test: Looking for a working non-Trivial Test Suite Example / Tutorial

    - by Robert S. Barnes
    The Boost.Test documentation and examples don't really seem to contain any non-trivial examples and so far the two tutorials I've found here and here while helpful are both fairly basic. I would like to have a master test suite for the entire project, while maintaining per module suites of unit tests and fixtures that can be run independently. I'll also be using a mock server to test various networking edge cases. I'm on Ubuntu 8.04, but I'll take any example Linux or Windows since I'm writing my own makefiles anyways.

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  • Pretty printing boost::unordered_map on gdb

    - by scooterman
    Hi all, recently I've started to use the excellent boost::unordered_map on my system, but got one drawback: I couldn't figure how to inspect its contents. Printing it on gdb gives me a table_ and a buckets_, but haven't found where are the items. Anyone has a clue about this?

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  • Why isn't the boost::shared_ptr -> operator inlined?

    - by Alan
    Since boost::shared_ptr could be called very frequently and simply returns a pointer, isn't the -> operator a good candidate for being inlined? T * operator-> () const // never throws { BOOST_ASSERT(px != 0); return px; } Would a good compiler automatically inline this anyway? Should I lose any sleep over this? :-)

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  • Boost multi_index ordered_unique Median Value

    - by Autopulated
    I would like to quickly retrieve the median value from a boost multi_index container with an ordered_unique index, however the index iterators aren't random access (I don't understand why they can't be, though this is consistent with std::set...). Is there a faster/neater way to do this other than incrementing an iterator container.size() / 2 times?

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  • Direct boost serialization to char array

    - by scooterman
    Hi all, Boost serialization doc's assert that the way to serialize/deserialize items is using a binary/text archive with a stream on the underlying structure. This works fine if I wan't to use the serialized data as an std::string, but my intention is to convert it directly to a char* buffer. How can I achieve this without creating a temporary string?

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  • C++ boost thread reusing threads

    - by aaa
    hi. I am trying to accomplish something like this: thread t; // create/initialize thread t.launch(); // launch thread. t.wait(); // wait t.launch(); // relaunch the same thread How to go about implementing something like this using boost threads? in essence, I need persistent relaunch-able thread. Thanks

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  • reading a random access file

    - by user1067332
    The file I create has text in it, but when i try to read it, the output is null. here is the file the creates the text file, it creates the file and puts it in the right postion import java.util.*; import java.io.*; public class CreateCustomerFile { public static void main(String[] args) throws IOException { int pos; RandomAccessFile it = new RandomAccessFile("CustomerFile.txt", "rw"); Scanner input = new Scanner(System.in); int id; String name; int zip; final int RECORDSIZE = 100; final int NUMRECORDS = 1000; final int STOP = 99; try { for(int x = 0; x < NUMRECORDS; ++x) { it.writeInt(0); it.writeUTF(""); it.writeInt(0); } } catch(IOException e) { System.out.println("Error: " + e.getMessage()); } finally { it.close(); } it = new RandomAccessFile("CustomerFile.txt","rw"); try { System.out.print("Enter ID number" + " or " + STOP + " to quit "); id = input.nextInt(); while(id != STOP) { input.nextLine(); System.out.print("Enter last name"); name = input.nextLine(); System.out.print("Enter zipcode "); zip = input.nextInt(); pos = id - 1; it.seek(pos * RECORDSIZE); it.writeInt(id); it.writeUTF(name); it.writeInt(zip); System.out.print("Enter ID number" + " or " + STOP + " to quit "); id = input.nextInt(); } } catch(IOException e) { System.out.println("Error: " + e.getMessage()); } finally { it.close(); } } } Here is the file to read, the pos is correct but ouput always goes to the error: null. import javax.swing.*; import java.io.*; public class CustomerItemOrder { public static void main(String[] args) throws IOException { int pos; RandomAccessFile it = new RandomAccessFile("CustomerFile.txt","rw"); String inputString; int id, zip; String name; final int RECORDSIZE = 100; final int STOP = 99; inputString = JOptionPane.showInputDialog(null, "Enter id or "+ STOP + " to quit"); id = Integer.parseInt(inputString); try { while(id != STOP) { pos = id -1 ; it.seek(pos * RECORDSIZE ); id = it.readInt(); name = it.readLine(); zip = it.readInt(); JOptionPane.showMessageDialog(null, "ID:" + id + " last name is " + name + " and zipcode is " + zip); inputString = JOptionPane.showInputDialog(null, "Enter id or " + STOP + " to quit"); id = Integer.parseInt(inputString); } } catch(IOException e) { System.out.println("Error: " + e.getMessage()); } finally { it.close(); } } }

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  • C++ boost wave, scoped macro

    - by aaa
    hello. Is it possible to have scoped macros using custom defined macros through boost wave? I know it should a possible with C++0x however I am working with regular C++. If it is possible, can you provide link or reference how to accomplish this? Thanks

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  • Why is my /dev/random so slow when using dd?

    - by Mikey
    I am trying to semi-securely erase a bunch of hard drives. The following is working at 20-50Mb/s dd if=/dev/zero of=/dev/sda But dd if=/dev/random of=/dev/sda seems not to work. Also when I type dd if=/dev/random of=stdout It only gives me a few bytes regardless of what I pass it for bs= and count= Am I using /dev/random wrong? What other info should I look for to move this troubleshooting forward? Is there some other way to do this with a script or something like makeMyLifeEasy | dd if=stdin of=/dev/sda Or something like that...

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  • any stl/boost functors to call operator()

    - by Voivoid
    template <typename T> struct Foo { void operator()(T& t) { t(); } }; Is there any standart or boost functor with the similar implementation? I need it to iterate over container of functors: std::for_each(beginIter, endIter, Foo<Bar>()); Or maybe there are other way to do it?

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  • Mixing C and C++, raw pointers and (boost) shared pointers

    - by oompahloompah
    I am working in C++ with some legacy C code. I have a data structure that (during initialisation), makes a copy of the structure pointed to a ptr passed to its initialisation pointer. Here is a simplification of what I am trying to do - hopefully, no important detail has been lost in the "simplification": /* C code */ typedef struct MyData { double * elems; unsigned int len; }; int NEW_mydata(MyData* data, unsigned int len) { // no error checking data->elems = (double *)calloc(len, sizeof(double)); return 0; } typedef struct Foo { MyData data data_; }; void InitFoo(Foo * foo, const MyData * the_data) { //alloc mem etc ... then assign the STRUCTURE foo.data_ = *thedata ; } C++ code ------------- typedef boost::shared_ptr<MyData> MyDataPtr; typedef std::map<std::string, MyDataPtr> Datamap; class FooWrapper { public: FooWrapper(const std::string& key) { MyDataPtr mdp = dmap[key]; InitFoo(&m_foo, const_cast<MyData*>((*mdp.get()))); } ~FooWrapper(); double get_element(unsigned int index ) const { return m_foo.elems[index]; } private: // non copyable, non-assignable FooWrapper(const FooWrapper&); FooWrapper& operator= (const FooWrapper&); Foo m_foo; }; int main(int argc, char *argv[]) { MyData data1, data2; Datamap dmap; NEW_mydata(&data1, 10); data1->elems[0] = static_cast<double>(22/7); NEW_mydata(&data2, 42); data2->elems[0] = static_cast<double>(13/21); boost::shared_ptr d1(&data1), d2(&data2); dmap["data1"] = d1; dmap["data2"] = d2; FooWrapper fw("data1"); //expect 22/7, get something else (random number?) double ret fw.get_element(0); } Essentially, what I want to know is this: Is there any reason why the data retrieved from the map is different from the one stored in the map?

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  • java random percentages

    - by erw
    I need to generate n percentages (integers between 0 and 100) such that the sum of all n numbers adds up to 100. If I just do nextInt() n times, each time ensuring that the parameter is 100 minus the previously accumulated sum, then my percentages are biased (i.e. the first generated number will usually be largest etc.). How do I do this in an unbiased way?

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  • Weighted random numbers in MATLAB

    - by yuk
    How to randomly pick up N numbers from a vector a with weight assigned to each number? Let's say: a = 1:3; % possible numbers weight = [0.3 0.1 0.2]; % corresponding weights In this case probability to pick up 1 should be 3 times higher than to pick up 2. Sum of all weights can be anything.

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  • How do i generate random data with RSA?

    - by acidzombie24
    After loading my RSACryptoServiceProvider rsa object i would like to create a key for my AES object. Since i dont need to store the AES key (i only need it to decrypt on my prv side) i figure i dont need to store it and i can generate it with my public key. I thought doing rsa.Encrypt(byte[] with 4 hardcoded bytes); would generate the data i need. It turns out everytime i call this function even with the same data i get different results. So theres no way for me to recreate the AES key if its different everytime. How can i generate data with RSA in a way that i can recreate anytime i need?

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  • Boost::asio::endpoint::size() and resize()

    - by p00ya
    hi. I was reading the boost endpoint documentation and saw size() and resize() member funcs. the documentation says: Gets the underlying size of the endpoint in the native type. what does this size represent and where can it be used/resized ? thanks.

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  • Custom InputIterator for Boost graph (BGL)

    - by Shadow
    Hi, I have a graph with custom properties to the vertices and edges. I now want to create a copy of this graph, but I don't want the vertices to be as complex as in the original. By this I mean that it would suffice that the vertices have the same indices (vertex_index_t) as they do in the original graph. Instead of doing the copying by hand I wanted to use the copy-functionality of boost::adjacency_list (s. http://www.boost.org/doc/libs/1_37_0/libs/graph/doc/adjacency_list.html): template <class EdgeIterator> adjacency_list(EdgeIterator first, EdgeIterator last, vertices_size_type n, edges_size_type m = 0, const GraphProperty& p = GraphProperty()) The description there says: The EdgeIterator must be a model of InputIterator. The value type of the EdgeIterator must be a std::pair, where the type in the pair is an integer type. The integers will correspond to vertices, and they must all fall in the range of [0, n). Unfortunately I have to admit that I don't quite get it how to define an EdgeIterator that is a model of InputIterator. Here's what I've succeded so far: template< class EdgeIterator, class Edge > class MyEdgeIterator// : public input_iterator< std::pair<int, int> > { public: MyEdgeIterator() {}; MyEdgeIterator(EdgeIterator& rhs) : actual_edge_it_(rhs) {}; MyEdgeIterator(const MyEdgeIterator& to_copy) {}; bool operator==(const MyEdgeIterator& to_compare) { return actual_edge_it_ == to_compare.actual_edge_it_; } bool operator!=(const MyEdgeIterator& to_compare) { return !(*this == to_compare); } Edge operator*() const { return *actual_edge_it_; } const MyEdgeIterator* operator->() const; MyEdgeIterator& operator ++() { ++actual_edge_it_; return *this; } MyEdgeIterator operator ++(int) { MyEdgeIterator<EdgeIterator, Edge> tmp = *this; ++*this; return tmp; } private: EdgeIterator& actual_edge_it_; } However, this doesn't work as it is supposed to and I ran out of clues. So, how do I define the appropriate InputIterator?

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  • Computationally simple Pseudo-Gaussian Distribution with varying mean and standard deviation?

    - by mstksg
    This picture from wikipedia has a nice example of the sort of functions I'd ideally like to generate http://en.wikipedia.org/wiki/File:Normal_Distribution_PDF.svg Right now I'm using the Irwin-Hall Distribution, which is more or less a Polynomial approximation of the Gaussian distribution...basically, you use uniform random number generator and iterate it x times, and take the average. The more iterations, the more like a Gaussian Distribution it is. It's pretty nice; however I'd like to be able to have one where I can vary the mean. For example, let's say I wanted a number between the range 0 and 10, but around 7. Like, the mean (if I repeated this function multiple times) would turn out to be 7, but the actual range is 0-10. Is there one I should look up, or should I work on doing some fancy maths with standard Gaussian Distributions?

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  • Efficiently generate a 16-character, alphanumeric string

    - by ensnare
    I'm looking for a very quick way to generate an alphanumeric unique id for a primary key in a table. Would something like this work? def genKey(): hash = hashlib.md5(RANDOM_NUMBER).digest().encode("base64") alnum_hash = re.sub(r'[^a-zA-Z0-9]', "", hash) return alnum_hash[:16] What would be a good way to generate random numbers? If I base it on microtime, I have to account for the possibility of several calls of genKey() at the same time from different instances. Or is there a better way to do all this? Thanks.

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