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  • Using memory mapping in C for reading binary

    - by user1320912
    I am trying to read data from a binary file and process it.It is a very large file so I thought I would use memory mapping. I am trying to use memory mapping so I can read the file byte by byte. I am getting a few compiler errors while doing this. I am doing this on a linux platform #include <unistd.h> #include <sys/types.h> #include <sys/mman.h> int fd; char *data; fd = open("data.bin", O_RDONLY); pagesize = 4000; data = mmap((caddr_t)0, pagesize, PROT_READ, MAP_SHARED, fd, pagesize); The errors i get are : caddr not initialized, R_RDONLY not initialized, mmap has too few arguments. Could someone help me out ?

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  • C++'s unordered_map / hash_map / Google's dense_hash - how to input binary data (buf+len) and insert

    - by shlomif
    Hi all, I have two questions about Google's dense_hash_map, which can be used instead of the more standard unordered_map or hash_map: How do I use an arbitrary binary data memory segment as a key: I want a buffer+length pair, which may still contain some NUL (\0) characters. I can see how I use a NUL-terminated char * string , but that's not what I want. How do I implement an operation where I look if a key exists, and if not - insert it and if it does return the pointer to the existing key and let me know what actually happened. I'd appreciate it if anyone can shed any light on this subject. Regards, -- Shlomi Fish

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  • Transferring binary file from web server to client

    - by Yan Cheng CHEOK
    Usually, when I want to transfer a web server text file to client, here is what I did import cgi print "Content-Type: text/plain" print "Content-Disposition: attachment; filename=TEST.txt" print filename = "C:\\TEST.TXT" f = open(filename, 'r') for line in f: print line Works very fine for ANSI file. However, say, I have a binary file a.exe (This file is in web server secret path, and user shall not have direct access to that directory path). I wish to use the similar method to transfer. How I can do so? What content-type I should use? Using print seems to have corrupted content received at client side. What is the correct method?

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  • Complexity in using Binary search and Trie

    - by user121196
    given a large list of alphabetically sorted words in a file,I need to write a program that, given a word x, determines if x is in the list. Preprocessing is ok since I will be calling this function many times over different inputs. priorties: 1. speed. 2. memory I already know I can use (n is number of words, m is average length of the words) 1. a trie, time is O(log(n)), space(best case) is O(log(n*m)), space(worst case) is O(n*m). 2. load the complete list into memory, then binary search, time is O(log(n)), space is O(n*m) I'm not sure about the complexity on tri, please correct me if they are wrong. Also are there other good approaches?

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  • Optimality of Binary Search

    - by templatetypedef
    Hello all- This may be a silly question, but does anyone know of a proof that binary search is asymptotically optimal? That is, if we are given a sorted list of elements where the only permitted operation on those objects is a comparison, how do you prove that the search can't be done in o(lg n)? (That's little-o of lg n, by the way.) Note that I'm restricting this to elements where the only operation permitted operation is a comparison, since there are well-known algorithms that can beat O(lg n) on expectation if you're allowed to do more complex operations on the data (see, for example, interpolation search). Thanks so much! This has really been bugging me since it seems like it should be simple but has managed to resist all my best efforts. :-)

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  • Program always returns binary '>>' : no operator found which takes a left-hand operand of type error

    - by Tom Ward
    So I've been set a task to create a temperature converter in C++ using this equation: Celsius = (5/9)*(Fahrenheit – 32) and so far I've come up with this (I've cut out the 10 lines worth of comments from the start so the code posted begins on line 11, if that makes any sense) #include <iostream> #include <string> #include <iomanip> #include <cmath> using namespace std; int main () { float celsius; float farenheit; std::cout << "**************************" << endl; std::cout << "*4001COMP-Lab5-Question 1*" << endl; std::cout << "**************************" << endl << endl; std::cout << "Please enter a temperature in farenheit: "; std::cin >> farenheit >> endl; std::cout << "Temperature (farenheit): " << endl; std::cout << "Temperature (celsius): " << celsius << endl; std::cin.get(); return 0; } Everytime I try to run this program I get a heap of errors with this one appearing every time: 1m:\visual studio 2010\projects\week 5\week 5\main.cpp(26): error C2678: binary '' : no operator found which takes a left-hand operand of type 'std::basic_istream<_Elem,_Traits' (or there is no acceptable conversion) I've tried everything I can think of to get rid of this error but it reappears every time, any idea on how to fix this?

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  • change label text from a VB6 binary (not source code)

    - by Jun
    Hi, we have a VB6 binary executable that comes with no source code. And we need to change the label text for that VB6 application from "AAA" to "BBB". Is there any way or tools that can do that? The closest tool I can find right now is microsoft UISpy, it can read all the other elements but not the label. I hope there is a tool that can change the resource in the .exe so that the label "AAA" will read "BBB". Or is it possible to write a wrapper application, it will launch the .exe, examine the application screen for "AAA" and change that to "BBB"? Thank you for your help!

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  • read text files containing binary data as a single matrix in matlab

    - by user1716595
    I have a text file which contains binary data in the following manner: 00000000000000000000000000000000001011111111111111111111111111111111111111111111111111111111110000000000000000000000000000000 00000000000000000000000000000000000000011111111111111111111111111111111111111111111111000111100000000000000000000000000000000 00000000000000000000000000000000000011111111111111111111111111111111111111111111111111111111100000000000000000000000000000000 00000000000000000000000000000000000111111111111111111111111111111111111111111111111111111111100000000000000000000000000000000 00000000000000000000000000000000000011111111111111111111111111111111111111111111111111111111100000000000000000000000000000000 00000000000000000000000000000000000000011111111111111111111111111111111111111111111111111111100000000000000000000000000000000 00000000000000000000000000000000000000011111111111111111111111111111111111111111111111000111110000000000000000000000000000000 00000000000000000000000000000000000000111111111111111111111111111111111111111111111111111111110000000000000000000000000000000 00000000000000000000000000000000000000000000111111111111111111111111111111111111110000000011100000000000000000000000000000000 00000000000000000000000000000000000000011111111111111111111111111111111111111111111111100111110000000000000000000000000000000 00000000000000000000000000000000000111111111111111111111111111111111111111111111111111110111110000000000000000000000000000000 00000000000000000000000000000000001111111111111111111111111111111111111111111111111111111111100000000000000000000000000000000 00000000000000000000000000000000000000001111111111111111111111111111111111111111111111000011100000000000000000000000000000000 00000000000000000000000000000000000000001111111111111111111111111111111111111111111111000011100000000000000000000000000000000 00000000000000000000000000000000000001111111111111111111111111111111111111111111111111111111000000000000000000000000000000000 00000000000000000000000000000000000000011111111111111111111111111111111111111111111110000011100000000000000000000000000000000 00000000000000000000000000000000000000000000011111111111111111111111111111111111100000000011100000000000000000000000000000000 00000000000000000000000000000000000000111111111111111111111111111111111111111111111111110111100000000000000000000000000000000 Plz note that each 1 or 0 is independent i.e the values are not decimal.I need to find the column wise sum of the file.There are 125 columns in all (here it is jumping onto the next line) and there are 840946 rows. I have tried textread,fscanf and a few other matlab commands but the result is that they all read each row in decimal format and create a 840946*1 array.I want to create a 840946*125 array to compute a column wise sum. Kindly help, Thanks!

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  • haskell. words into binary numbers

    - by Katja
    I need to convert words into binary numbers. With a bit help of yours I got this blCo::String -> Integer blCo x = num2bin(lett2num x) blCo (x:xs) | x:xs = num2bin(lett2num x):blCo xs num2lett :: Int -> Char num2lett n | (n <= ord 'A') && (n <= ord 'Z') = chr(ord 'A'+ n - 1) | (n <= ord 'a') && (n <= ord 'Z') = chr(ord 'A'+ n - 1) num2bin :: Integer -> String num2bin n | n >= 0 = concatMap show (reverse ( n2b n)) | otherwise = error "num2bin: negative number" where n2b 0 = [] n2b n = n `mod` 2 : n2b (n `div` 2) he tells me a mistake.I dont undertsand it mistake: Couldn't match expected type `Char' against inferred type `String' In the first argument of `lett2num', namely `x' In the first argument of `num2bin', namely `(lett2num x)' In the expression: num2bin (lett2num x)

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  • Java print binary number using bit-wise operator

    - by user69514
    Hi I am creating a method that will take a number and print it along with its binary representation. The problems is that my method prints all 0's for any positive number, and all 1's for any negative number private static void display( int number ){ System.out.print(number + "\t"); int mask = 1 << 31; for(int i=1; i<=32; i++) { if( (mask & number) != 0 ) System.out.print(1); else System.out.print(0); if( (i % 4) == 0 ) System.out.print(" "); } }

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  • Java : Count even values in a Binary Search Tree recursively

    - by user307682
    Hi, I need to find out how many even values are contained in a binary tree. this is my code. private int countEven(BSTNode root){ if ((root == null)|| (root.value%2==1)) return 0; return 1+ countEven(root.left) + countEven(root.right); } this i just coded as i do not have a way to test this out. I'm not able to test it out at the moment but need an answer so badly. any help is deeply appreciated.

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  • Export SQL Binary/BLOB Data?

    - by davemackey
    Recently a software application we utilize upgraded from ASP to ASP.NET. In the process they abandoned the old web-based product and rewrote the entire UI, using new DB tables. The old DB tables still exist in the database and contain legacy files in binary or blob formats. I'm wondering if there is an easy way to export all these legacy files from the database to the filesystem (NTFS)? Then we could delete these old unused tables and save a few GB of space in the DB backups, etc.

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  • Dividing n-bit binary integers

    - by Julian
    Was wondering if anyone could help me with creating a pseudocode for how to go about dividing n-bit binary integers. Here is what I'm thinking could possibly work right now, could someone correct this if I'm wrong: divide (x,y) if x=0: return (0,0) //(quotient, remainder) (q,r) = divide(floor(x/2), y) q=2q, r=2r if x is odd: r = r+1 if r >= y: r = r-y, q = q+1 return (q,r) Would you guys say that this general pseudocode algorithm would accomplish the intended task of dividing n-bit numbers or am I missing something in my psuedocode before I start coding up something that's wrong?

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  • Fastest way to convert a binary file to SQLite database

    - by chown
    I've some binary files and I'm looking for a way to convert each of those files to a SQLite database. I've already tried C# but the performance is too slow. I'm seeking an advice on how and what programming language should be the best to perform this kind of conversion. Though I prefer any Object Oriented Language more (like C#, Java etc), I'm open for any programming language that boosts up the conversion. I don't need a GUI frontend for the conversion, running the script/program from console is okay. Thanks in advance

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  • Implementing an iterator over binary tree using C++ 11

    - by user1459339
    I would like to create an iterator over the binary tree so as to be able to use range-based for loop. I understand I ought to implement the begin() and end() function first. Begin should probably point to the root. According to the specification, however, the end() functions returns "the element following the last valid element". Which element (node) is that? Would it not be illegal to point to some "invalid" place? The other thing is the operator++. What is the best way to return "next" element in tree? I just need some advice to begin with this programming.

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  • Trying to serialize and unserialze a Binary search tree to a file

    - by ClearMist
    I am trying to find a way to use these methods to save and restore a binary search tree that contains names and phone numbers in each node. I am just very lost and how to go about doing this. 'public void save(String fileName) { // TODO : implement this method. // save bst to its original shape. } public void restore(String fileName) { // TODO : implement this method. // restore bst from a file, if file exists. // do nothing, otherwise. File fichier = new File(fileName); if (fichier.exists()) { } }'

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  • How to implement Priority Queues in Python?

    - by dragosrsupercool
    Sorry for such a silly question but Python docs are confusing.. . Link 1: Queue Implementation http://docs.python.org/library/queue.html It says thats Queue has a contruct for priority queue. But I could not find how to implement it. class Queue.PriorityQueue(maxsize=0) Link 2: Heap Implementation http://docs.python.org/library/heapq.html Here they says that we can implement priority queues indirectly using heapq pq = [] # list of entries arranged in a heap entry_finder = {} # mapping of tasks to entries REMOVED = '<removed-task>' # placeholder for a removed task counter = itertools.count() # unique sequence count def add_task(task, priority=0): 'Add a new task or update the priority of an existing task' if task in entry_finder: remove_task(task) count = next(counter) entry = [priority, count, task] entry_finder[task] = entry heappush(pq, entry) def remove_task(task): 'Mark an existing task as REMOVED. Raise KeyError if not found.' entry = entry_finder.pop(task) entry[-1] = REMOVED def pop_task(): 'Remove and return the lowest priority task. Raise KeyError if empty.' while pq: priority, count, task = heappop(pq) if task is not REMOVED: del entry_finder[task] return task raise KeyError('pop from an empty priority queue' Which is the most efficient priority queue implementation in python? And how to implement it?

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  • Is it safe to convert a mysqlpp::sql_blob to a std::string?

    - by Runcible
    I'm grabbing some binary data out of my MySQL database. It comes out as a mysqlpp::sql_blob type. It just so happens that this BLOB is a serialized Google Protobuf. I need to de-serialize it so that I can access it normally. This gives a compile error, since ParseFromString() is not intended for mysqlpp:sql_blob types: protobuf.ParseFromString( record.data ); However, if I force the cast, it compiles OK: protobuf.ParseFromString( (std::string) record.data ); Is this safe? I'm particularly worried because of this snippet from the mysqlpp documentation: "Because C++ strings handle binary data just fine, you might think you can use std::string instead of sql_blob, but the current design of String converts to std::string via a C string. As a result, the BLOB data is truncated at the first embedded null character during population of the SSQLS. There’s no way to fix that without completely redesigning either String or the SSQLS mechanism." Thanks for your assistance!

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  • Java "compare cannot be resolved to a type" error

    - by King Triumph
    I'm getting a strange error when attempting to use a comparator with a binary search on an array. The error states that "compareArtist cannot be resolved to a type" and is thrown by Eclipse on this code: Comparator<Song> compare = new Song.compareArtist(); I've done some searching and found references to a possible bug with Eclipse, although I have tried the code on a different computer and the error persists. I've also found similar issues regarding the capitalization of the compare method, in this case compareArtist. I've seen examples where the first word in the method name is capitalized, although it was my understanding that method names are traditionally started with a lower case letter. I have experimented with changing the capitalization but nothing has changed. I have also found references to this error if the class doesn't import the correct package. I have imported java.util in both classes in question, which to my knowledge allows the use of the Comparator. I've experimented with writing the compareArtist method within the class that has the binary search call as well as in the "Song" class, which according to my homework assignment is where it should be. I've changed the constructor accordingly and the issue persists. Lastly, I've attempted to override the Comparator compare method by implementing Comparator in the Song class and creating my own method called "compare". This returns the same error. I've only moved to calling the comparator method something different than "compare" after finding several examples that do the same. Here is the relevant code for the class that calls the binary search that uses the comparator. This code also has a local version of the compareArtist method. While it is not being called currently, the code for this method is the same as the in the class Song, where I am trying to call it from. Thanks for any advice and insight. import java.io.*; import java.util.*; public class SearchByArtistPrefix { private Song[] songs; // keep a direct reference to the song array private Song[] searchResults; // holds the results of the search private ArrayList<Song> searchList = new ArrayList<Song>(); // hold results of search while being populated. Converted to searchResults array. public SearchByArtistPrefix(SongCollection sc) { songs = sc.getAllSongs(); } public int compareArtist (Song firstSong, Song secondSong) { return firstSong.getArtist().compareTo(secondSong.getArtist()); } public Song[] search(String artistPrefix) { String artistInput = artistPrefix; int searchLength = artistInput.length(); Song searchSong = new Song(artistInput, "", ""); Comparator<Song> compare = new Song.compareArtist(); int search = Arrays.binarySearch(songs, searchSong, compare);

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  • How do you read data from a ADODB stream in ASP as byte values?

    - by user89691
    I have an ASP routine that gets a binary file's contents and writes it to a stream. The intention is to read it from the stream and process it st the server. So I have: ResponseBody = SomeRequest (SomeURL) ; var BinaryInputStream = Server.CreateObject ("ADODB.Stream") ; BinaryInputStream.Type = 1 ; // binary BinaryInputStream.Open ; BinaryInputStream.Write (ResponseBody) ; BinaryInputStream.Position = 0 ; var DataByte = BinaryInputStream.Read (1) ; Response.Write (typeof (DataByte)) ; // displays "unknown" How do I get the byte value of the byte I have just read from the stream? Asc () and byte () don't work (JScript) TIA

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  • reading unformatted fortran file in matlab - which precision?

    - by Griff
    I have just written out a file: real*8 :: vol_cel real*8, dimension(256,256,256) :: dense [... some operations] open(unit=8,file=fname,form="unformatted") write(8)dense(:,:,:)/vol_cell close(8) dense and vol_cell are real*8 variables. My code to read this in in Matlab: fid = fopen(fname,'r'); mesh_raw = fread(fid,256*256*256,'double'); fclose(fid); The min and max values clearly show that it is not reading it in correctly (Min is 0 and max is a largish positive real*8). min = 3.3622e+38 max = -3.3661e+38 What precision do I need to set in Matlab to make it read in the unformatted Fortran file? A somewhat related question: This Matlab code I am using reads binary files OK but not unformatted files. Though I am generating this new data on my Mac OSX using gfortran. It doesn't recognize form="binary" so I can't do it that way. Do I need to add some library?

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  • Best way to bundles photos with app: files or in sqlite database?

    - by Bryan Denny
    Lets say that I have an app that lets you browse through a listing of cars found in a Sqlite database. When you click on a car in the listing, it'll open up a view with the description of the car and a photo of the car. My question is: should I keep the photo in the database as a binary data column in the row for this specific car, or should I have the photo somewhere in the resources directory? Which is better to do? Are there any limitations of Sqlite in terms of how big a binary data column can be? The database will be pretty much be read only and bundled with the app (so the user wouldn't be inserting any cars and their photos).

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  • I need an efficient protocol between webservices that are more or less supported by all major langua

    - by corgrath
    Hey all. I am looking for a fast and efficient protocol that can be used between different web services to send text-data (not binary data). Doesn't matter if the protocol is binary or text base. Some conditions: I has to be more "efficient" than normal XML which adds a lot of extra data and the tools to read/write is too heavy It has to be "supported" by most major languages, meaning it cannot only be available for one specific language. At the moment, both Java and PHP have to be able to talk to each other using this protocol. I have already looked at: XML - which I am currently using. Hessian 2 -which works perfectly in Java, but the PHP-support is out of date JSON -the different between JSON and XML is only minor Any suggestions are welcome!

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  • How can I make my binary file is served as binary, not text when user choose "Save Linked File As..." in Safari?

    - by Eonil
    I'm serving a binary file (.IPA) with Ubuntu/Apache 2.2. When I have chosen Save Linked File As... in Safari, it says it's text file. And it guides me to add .txt extension. However it does not add any extra extension when I download it just clicking link. I added line AddType application/octet-stream .ipa in apache configuration file. I don't know what's wrong with this. Is this a bug of Safari or my misconfiguration? (1) If it caused by bug, how can I avoid this? (2) Or if it caused by misconfiguration, what should I do?

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