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  • [PHP] md5(uniqid) makes sense for random unique tokens?

    - by Exception e
    I want to create a token generator that generates tokens that cannot be guessed by the user and that are still unique (to be used for password resets and confirmation codes). I often see this code; does it make sense? md5(uniqid(rand(), true)); According to a comment uniqid($prefix, $moreEntopy = true) yields first 8 hex chars = Unixtime, last 5 hex chars = microseconds. I don't know how the $prefix-parameter is handled.. So if you don't set the $moreEntopy flag to true, it gives a predictable outcome. QUESTION: But if we use uniqid with $moreEntopy, what does hashing it with md5 buy us? Is it better than: md5(mt_rand())

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  • How to get N random string from a {a1|a2|a3} format string?

    - by Pentium10
    Take this string as input: string s="planets {Sun|Mercury|Venus|Earth|Mars|Jupiter|Saturn|Uranus|Neptune}" How would I choose randomly N from the set, then join them with comma. The set is defined between {} and options are separated with | pipe. The order is maintained. Some output could be: string output1="planets Sun, Venus"; string output2="planets Neptune"; string output3="planets Earth, Saturn, Uranus, Neptune"; string output4="planets Uranus, Saturn";// bad example, order is not correct Java 1.5

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  • How can I generate a random human-readable colour from a seed? C#

    - by SLC
    Got a logfile, and it has all kinds of text in it. Currently it is just displayed as one colour, and each entry says something like: Log from section 1: Some text here Log from section 125: Some text here Log from section 17: Some text here Log from section 1: Some text here Log from section 125: Some text here Log from section 1: Some text here Log from section 17: Some text here Now the logfile is displayed in real time, and it would be nice to make the rows with the same section number the same colour. However there could be potentially quite a large range of numbers. What I want to do is create a method that will take a number, and randomly generate a unique colour. The colour must be readable against a black background though, so #000000 is no good, nor is #101010 or anything too dark to read. Ideally two similar numbers will not produce the same colour because in the above examples, the numbers 1 and 17 might be too similar, and some numbers might be in the 10,000 range. Any ideas on this?

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  • Creating a newspaper that effects the game's economy?

    - by zardon
    I am writing a game in Objective C/cocos2d where a newspaper is a central part of what controls or rather effects the game's world economy as well as what a city might do (such as increase X, reduce Y) The newspaper is a bit like a "Chance card" in Monopoly, it has an effect on something. My question is, what is the best way to do write a newspaper that has both a random and specific effect within the game. Would the best strategy be to write out all the things a newspaper can affect, a PLIST of headlines (with placeholders). I think Tiny Tower uses a PLIST of events and it randomly picks an event, but I'm not sure how it actually parses it because certain events do different things. But then how do I parse all the scenarios that a newspaper can deliver? A big switch statement seems very long and complicated to do. I am wondering if there is a simpler way to handle this kind of thing. Related to this is that there might be no news that day and I'm not sure what the newspaper should display, should it just display the last headline? So, in summary. 1) A newspaper generates a headline, it affects different things, such as the world economy, prices, how city reacts 2) I need the newspaper to generate headlines (although there may be days when there are no headlines at all), but I am not sure how to parse it without using a big-ass switch statement. Thanks in advance.

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  • Randomly and uniquely iterating over a range

    - by Synetech
    Say you have a range of values (or anything else) and you want to iterate over the range and stop at some indeterminate point. Because the stopping value could be anywhere in the range, iterating sequentially is no good because it causes the early values to be accessed more often than later values (which is bad for things that wear out), and also because it reduces performance since it must traverse extra values. Randomly iterating is better because it will (on average) increase the hit-rate so that fewer values have to be accessed before finding the right one, and also distribute the accesses more evenly (again, on average). The problem is that the standard method of randomly jumping around will result in values being accessed multiple times, and has no automatic way of determining when each value has been checked and thus the whole range has been exhausted. One simplified and contrived solution could be to make a list of each value, pick one at random, then remove it. Each time through the loop, you pick one fromt he set of remaining items. Unfortunately this only works for small lists. As a (forced) example, say you are creating a game where the program tries to guess what number you picked and shows how many guess it took. The range is between 0-255 and instead of asking Is it 0? Is it 1? Is it 2?…, you have it guess randomly. You could create a list of 255 numbers, pick randomly and remove it. But what if the range was between 0-232? You can’t really create a 4-billion item list. I’ve seen a couple of implementations RNGs that are supposed to provide a uniform distribution, but none that area also supposed to be unique, i.e., no repeated values. So is there a practical way to randomly, and uniquely iterate over a range?

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  • Playback random section from multiple videos changing every 5 minutes

    - by brian
    I'm setting up the A/V for a holiday party this weekend and have an idea that I'm not sure how to implement. I have a bunch of Christmas movies (Christmas Vacation, A Christmas Story, It's a Wonderful Life, etc.) that I'd like to have running continuously at the party. The setup is a MacBook connected to a projector. I want this to be a background ambiance thing so it's going to be running silently. Since all of the movies are in the +1 hour range, instead of just playing them all through from beginning to end, I'd like to show small samples randomly and continuously. Ideally the way it would work is that every five minutes it would choose a random 5-minute sample from a random movie in the playlist/directory and display it. Once that clip is over, it should choose another clip and do some sort of fade/wipe to the chosen clip. I'm not sure where to start on this, beginning with what player I should use. Can VLC do something like this? MPlayer? If there's a player with an extensive scripting language (support for rand(), video length discovery, random video access). If so, I will probably be able to RTFM and get it working; it's just that I don't have time to backtrack from dead-ends so I'd like to start off on the right track. Any suggestions?

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  • "Expected initializer before '<' token" in header file

    - by Sarah
    I'm pretty new to programming and am generally confused by header files and includes. I would like help with an immediate compile problem and would appreciate general suggestions about cleaner, safer, slicker ways to write my code. I'm currently repackaging a lot of code that used to be in main() into a Simulation class. I'm getting a compile error with the header file for this class. I'm compiling with gcc version 4.2.1. // Simulation.h #ifndef SIMULATION_H #define SIMULATION_H #include <cstdlib> #include <iostream> #include <cmath> #include <string> #include <fstream> #include <set> #include <boost/multi_index_container.hpp> #include <boost/multi_index/hashed_index.hpp> #include <boost/multi_index/member.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/mem_fun.hpp> #include <boost/multi_index/composite_key.hpp> #include <boost/shared_ptr.hpp> #include <boost/tuple/tuple_comparison.hpp> #include <boost/tuple/tuple_io.hpp> #include "Parameters.h" #include "Host.h" #include "rng.h" #include "Event.h" #include "Rdraws.h" typedef multi_index_container< // line 33 - first error boost::shared_ptr< Host >, indexed_by< hashed_unique< const_mem_fun<Host,int,&Host::getID> >, // 0 - ID index ordered_non_unique< tag<age>,const_mem_fun<Host,int,&Host::getAgeInY> >, // 1 - Age index hashed_non_unique< tag<household>,const_mem_fun<Host,int,&Host::getHousehold> >, // 2 - Household index ordered_non_unique< // 3 - Eligible by age & household tag<aeh>, composite_key< Host, const_mem_fun<Host,int,&Host::getAgeInY>, const_mem_fun<Host,bool,&Host::isEligible>, const_mem_fun<Host,int,&Host::getHousehold> > >, ordered_non_unique< // 4 - Eligible by household (all single adults) tag<eh>, composite_key< Host, const_mem_fun<Host,bool,&Host::isEligible>, const_mem_fun<Host,int,&Host::getHousehold> > >, ordered_non_unique< // 5 - Household & age tag<ah>, composite_key< Host, const_mem_fun<Host,int,&Host::getHousehold>, const_mem_fun<Host,int,&Host::getAgeInY> > > > // end indexed_by > HostContainer; typedef std::set<int> HHSet; class Simulation { public: Simulation( int sid ); ~Simulation(); // MEMBER FUNCTION PROTOTYPES void runDemSim( void ); void runEpidSim( void ); void ageHost( int id ); int calcPartnerAge( int a ); void executeEvent( Event & te ); void killHost( int id ); void pairHost( int id ); void partner2Hosts( int id1, int id2 ); void fledgeHost( int id ); void birthHost( int id ); void calcSI( void ); double beta_ij_h( int ai, int aj, int s ); double beta_ij_nh( int ai, int aj, int s ); private: // SIMULATION OBJECTS double t; double outputStrobe; int idCtr; int hholdCtr; int simID; RNG rgen; HostContainer allHosts; // shared_ptr to Hosts - line 102 - second error HHSet allHouseholds; int numInfecteds[ INIT_NUM_AGE_CATS ][ INIT_NUM_STYPES ]; EventPQ currentEvents; // STREAM MANAGEMENT void writeOutput(); void initOutput(); void closeOutput(); std::ofstream ageDistStream; std::ofstream ageDistTStream; std::ofstream hhDistStream; std::ofstream hhDistTStream; std::string ageDistFile; std::string ageDistTFile; std::string hhDistFile; std::string hhDistTFile; }; #endif I'm hoping the other files aren't so relevant to this problem. When I compile with g++ -g -o -c a.out -I /Applications/boost_1_42_0/ Host.cpp Simulation.cpp rng.cpp main.cpp Rdraws.cpp I get Simulation.h:33: error: expected initializer before '<' token Simulation.h:102: error: 'HostContainer' does not name a type and then a bunch of other errors related to not recognizing the HostContainer. It seems like I have all the right Boost #includes for the HostContainer to be understood. What else could be going wrong? I would appreciate immediate suggestions, troubleshooting tips, and other advice about my code. My plan is to create a "HostContainer.h" file that includes the typedef and structs that define its tags, similar to what I'm doing in "Event.h" for the EventPQ container. I'm assuming this is legal and good form.

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  • Randomly generate directed graph on a grid

    - by Talon876
    I am trying to randomly generate a directed graph for the purpose of making a puzzle game similar to the ice sliding puzzles from Pokemon. This is essentially what I want to be able to randomly generate: http://bulbanews.bulbagarden.net/wiki/Crunching_the_numbers:_Graph_theory. I need to be able to limit the size of the graph in an x and y dimension. In the example given in the link, it would be restricted to an 8x4 grid. The problem I am running into is not randomly generating the graph, but randomly generating a graph, which I can properly map out in a 2d space, since I need something (like a rock) on the opposite side of a node, to make it visually make sense when you stop sliding. The problem with this is that sometimes the rock ends up in the path between two other nodes or possibly on another node itself, which causes the entire graph to become broken. After discussing the problem with a few people I know, we came to a couple of conclusions that may lead to a solution. Including the obstacles in the grid as part of the graph when constructing it. Start out with a fully filled grid and just draw a random path and delete out blocks that will make that path work. The problem then becomes figuring out which ones to delete to avoid introducing an additional, shorter path. We were also thinking a dynamic programming algorithm may be beneficial, though none of us are too skilled with creating dynamic programming algorithms from nothing. Any ideas or references about what this problem is officially called (if it's an official graph problem) would be most helpful. Here are some examples of what I have accomplished so far by just randomly placing blocks and generating the navigation graph from the chosen start/finish. The idea (as described in the previous link) is you start at the green S and want to get to the green F. You do this by moving up/down/left/right and you continue moving in the direction chosen until you hit a wall. In these pictures, grey is a wall, white is the floor, and the purple line is the minimum length from start to finish, and the black lines and grey dots represented possible paths. Here are some bad examples of randomly generated graphs: http://i.stack.imgur.com/9uaM6.png Here are some good examples of randomly generated (or hand tweaked) graphs: i.stack.imgur.com/uUGeL.png (can't post another link, sorry) I've also seemed to notice the more challenging ones when actually playing this as a puzzle are ones which have lots of high degree nodes along the minimum path.

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  • Portable C++ library for IPC (processes and shared memory), Boost vs ACE vs Poco?

    - by user363778
    Hi, I need a portable C++ library for doing IPC. I used fork() and SysV shared memory until now but this limits me to Linux/Unix. I found out that there are 3 major C++ libraries that offer a portable solution (including Windows and Mac OS X). I really like Boost, and would like to use it but I need processes and it seems like that this is only an experimental branch until now!? I have never heard of ACE or POCO before and thus I am stuck I do not know which one to choose. I need fork(), sleep() (usleep() would be great) and shared memory of course. Performance and documentation are also important criteria. Thanks, for your Help!

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  • Using boost.python to import a method with opencv calls but failing due to symbols not being found a

    - by nmz787
    So I don't have the code right now, as I am not home... but i used the boost library for python in C++ to allow python to access a function called something like loadImageIntoMainWindow(string filepath) in the C++ source code the method calls opencv methods that are imported at the top of the file, I included opencv in my Jamroot file, and also found a way to compile and link manually on the command line... in either case when I run my python file it complains that the symbols aren't found for the first function call to an opencv method... I will update as soon as I get home with the C++, the command line compilation lines, the Jamroot, and the python files

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  • Parallel Programming. Boost's MPI, OpenMP, TBB, or something else?

    - by unknownthreat
    Hello, I am totally a novice in parallel programming, but I do know how to program C++. Now, I am looking around for parallel programming library. I just want to give it a try, just for fun, and right now, I found 3 APIs, but I am not sure which one should I stick with. Right now, I see Boost's MPI, OpenMP and TBB. For anyone who have experienced with any of these 3 API (or any other parallelism API), could you please tell me the difference between these? Are there any factor to consider, like AMD or Intel architecture?

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  • Multi-Core Programming. Boost's MPI, OpenMP, TBB, or something else?

    - by unknownthreat
    Hello, I am totally a novice in Multi-Core Programming, but I do know how to program C++. Now, I am looking around for Multi-Core Programming library. I just want to give it a try, just for fun, and right now, I found 3 APIs, but I am not sure which one should I stick with. Right now, I see Boost's MPI, OpenMP and TBB. For anyone who have experienced with any of these 3 API (or any other API), could you please tell me the difference between these? Are there any factor to consider, like AMD or Intel architecture?

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  • How to attach boost::shared_ptr (or another smart pointer) to reference counter of object's parent?

    - by Checkers
    I remember encountering this concept before, but can't find it in Google now. If I have an object of type A, which directly embeds an object of type B: class A { B b; }; How can I have a smart pointer to B, e. g. boost::shared_ptr<B>, but use reference count of A? Assume an instance of A itself is heap-allocated I can safely get its shared count using, say, enable_shared_from_this.

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  • How do I know if a boost thread is done ?

    - by jules
    I am using boost::thread to process messages in a queue. When a first message comes I start a message processing thread. When a second message comes I check if the message processing thread is done. if it is done I start a new one if it is not done I don nothing. How do I know if the thread is done ? I tried with joinable() but it is not working, as when the thread is done, it is still joinable. I also tried to interrupt the process at once, and add an interruption point at the end of my thread, but it did not work. Thanks

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  • How do I insert format str and don't remove the matched regular expression in input string in boost:

    - by Yadollah
    I want to put space between punctuations and other words in a sentence. But boost::regex_replace() replaces the punctuation with space, and I want to keep a punctuation in the sentence! for example in this code the output should be "Hello . hi , " regex e1("[.,]"); std::basic_string<char> str = "Hello.hi,"; std::basic_string<char> fmt = " "; cout<<regex_replace(str, e1, fmt)<<endl; Can you help me?

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  • iPhone OS: Fetching a random entity instance using NSPredicate Nsfetchrequest and core data

    - by nickthedude
    Working on an app where I have a large collections of managed objects against which I want to fetch a few random instances. My question is, is there any way I can use NSPredicate and NSFetchRequest to return several objects at random. I saw that you could actually add a NSFetchRequest into the entity using the data modeler, any way to do the random fetch using this? Also what would be the best method for determining the "count" of a table so I can set the bounds of the random number generator. let me know if you need more details. Thanks! Nick

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  • Salt question - using a "random salt"

    - by barfoon
    Hey everyone, Further to my question here, I have another question regarding salts. When someone says "use a random salt" to pre/append to a password, does this mean: Creating a static a 1 time randomly generated string of characters, or Creating a string of characters that changes at random every time a password is created? If the salt is random for every user and stored along with the hashed password, how is the original salt ever retrieved back for verification? Thanks!

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  • How Can I Generate Random Unqiue Numbers in C#

    - by peace
    public int GenPurchaseOrderNum() { Random random = new Random(); _uniqueNum = random.Next(13287, 21439); return UniqueNum; } I removed unique constraint from the PONumber column in the db because an employee should only generate P.O. # when the deal is set. Otherwise, P.O. # would have 0. P.O. Number used to have unique constraint, this forces employee to generate P.O. in all cases so the db doesn't throw unique constraint error. Since i removed the unique constraint, any quote doesn't have P.O. will carry 0 value. Otherwise, a unique value is generated for P.O. #. However, i don't have a unique constraint in db which makes it hard for me to know whether the application generated P.O. # is unique or not. What should i do? I hope my question is clear enough

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