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  • Python file iterator over a binary file with newer idiom.

    - by drewk
    In Python, for a binary file, I can write this: buf_size=1024*64 # this is an important size... with open(file, "rb") as f: while True: data=f.read(buf_size) if not data: break # deal with the data.... With a text file that I want to read line-by-line, I can write this: with open(file, "r") as file: for line in file: # deal with each line.... Which is shorthand for: with open(file, "r") as file: for line in iter(file.readline, ""): # deal with each line.... This idiom is documented in PEP 234 but I have failed to locate a similar idiom for binary files. I have tried this: >>> with open('dups.txt','rb') as f: ... for chunk in iter(f.read,''): ... i+=1 >>> i 1 # 30 MB file, i==1 means read in one go... I tried putting iter(f.read(buf_size),'') but that is a syntax error because of the parens after the callable in iter(). I know I could write a function, but is there way with the default idiom of for chunk in file: where I can use a buffer size versus a line oriented? Thanks for putting up with the Python newbie trying to write his first non-trivial and idiomatic Python script.

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  • MySQL Binary Storage using BLOB VS OS File System: large files, large quantities, large problems.

    - by Quantico773
    Hi Guys, Versions I am running (basically latest of everything): PHP: 5.3.1 MySQL: 5.1.41 Apache: 2.2.14 OS: CentOS (latest) Here is the situation. I have thousands of very important documents, ranging from customer contracts to voice signatures (recordings of customer authorisation for contracts), with file types including, but not limited to jpg, gif, png, tiff, doc, docx, xls, wav, mp3, pdf, etc. All of these documents are currently stored on several servers including Windows 32 bit, CentOS and Mac, among others. Some files are also stored on employees desktop computers and laptops, and some are still hard copies stored in hundreds of boxes and filing cabinets. Now because customers or lawyers could demand evidence of contracts at any time, my company has to be able to search and locate the correct document(s) effectively, for this reason ALL of these files have to be digitised (if not already) and correlated into some sort of order for searching and accessing. As the programmer, I have created a full Customer Relations Management tool that the whole company uses. This includes Customer Profiles management, Order and job Tracking tools, Job/sale creation and management modules, etc, and at the moment any file that is needed at a customer profile level (drivers licence, credit authority, etc) or at a job/sale level (contracts, voice signatures, etc) can be uploaded to the server and sits in a parent/child hierarchy structure, just like Windows Explorer or any other typical file managment model. The structure appears as such: drivers_license |- DL_123.jpg voice_signatures |- VS_123.wav |- VS_4567.wav contracts So the files are uplaoded using PHP and Apache, and are stored in the file system of the OS. At the time of uploading, certain information about the file(s) is stored in a MySQL database. Some of the information stored is: TABLE: FileUploads FileID CustomerID (the customer id that the file belongs to, they all have this.) JobID/SaleID (the id of the job/sale associated, if any.) FileSize FileType UploadedDateTime UploadedBy FilePath (the directory path the file is stored in.) FileName (current file name of uploaded file, combination of CustomerID and JobID/SaleID if applicable.) FileDescription OriginalFileName (original name of the source file when uploaded, including extension.) So as you can see, the file is linked to the database by the File Name. When I want to provide a customers' files for download to a user all I have to do is "SELECT * FROM FileUploads WHERE CustomerID = 123 OR JobID = 2345;" and this will output all the file details I require, and with the FilePath and FileName I can provide the link for download. http... server / FilePath / FileName There are a number of problems with this method: Storing files in this "database unconcious" environment means data integrity is not kept. If a record is deleted, the file may not be deleted also, or vice versa. Files are strewn all over the place, different servers, computers, etc. The file name is the ONLY thing matching the binary to the database and customer profile and customer records. etc, etc. There are so many reasons, some of which are described here: http://www.dreamwerx.net/site/article01 . Also there is an interesting article here too: sietch.net/ViewNewsItem.aspx?NewsItemID=124 . SO, after much research I have pretty much decided I am going to store ALL of these files in the database, as a BLOB or LONGBLOB, but there are still many considerations before I do this. I know that storing them in the database is a viable option, however there are a number of methods of storing them. I also know storing them is one thing; correlating and accessing them in a manageable way is another thing entirely. The article provided at this link: dreamwerx.net/site/article01 describes a way of splitting the uploaded binary files into 64kb chunks and storing each chunk with the FileID, and then streaming the actual binary file to the client using headers. This is a really cool idea since it alleviates preassure on the servers memory; instead of loading an entire 100mb file into the RAM and then sending it to the client, it is doing it 64kb at a time. I have tried this (and updated his scripts) and this is totally successful, in a very small frame of testing. So if you are in agreeance that this method is a viable, stable and robust long-term option to store moderately large files (1kb to couple hundred megs), and large quantities of these files, let me know what other considerations or ideas you have. Also, I am considering getting a current "File Management" PHP script that gives an interface for managing files stored in the File System and converting it to manage files stored in the database. If there is already any software out there that does this, please let me know. I guess there are many questions I could ask, and all the information is up there ^^ so please, discuss all aspects of this and we can pass ideas back and forth and teach each other. Cheers, Quantico773

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  • SerializationException Occurring Only in Release Mode

    - by Calvin Nguyen
    Hi, I am working on an ASP.NET web app using Visual Studio 2008 and a third-party library. Things are fine in my development environment. Things are also good if the web app is deployed in Debug configuration. However, when it is deployed in Release mode, SerializationExceptions appear intermittently, breaking other functionality. In the Windows event log, the following error can be seen: "An unhandled exception occurred and the process was terminated. Application ID: DefaultDomain Process ID: 3972 Exception: System.Runtime.Serialization.SerializationException Message: Unable to find assembly 'MyThirdPartyLibrary, Version=1.234.5.67, Culture=neutral, PublicKeyToken=3d67ed1f87d44c89'. StackTrace: at System.Runtime.Serialization.Formatters.Binary.BinaryAssemblyInfo.GetAssembly( ) at System.Runtime.Serialization.Formatters.Binary.ObjectReader.GetType(BinaryAsse mblyInfo assemblyInfo, String name) at System.Runtime.Serialization.Formatters.Binary.ObjectMap..ctor(String objectName, String[] memberNames, BinaryTypeEnum[] binaryTypeEnumA, Object[] typeInformationA, Int32[] memberAssemIds, ObjectReader objectReader, Int32 objectId, BinaryAssemblyInfo assemblyInfo, SizedArray assemIdToAssemblyTable) at System.Runtime.Serialization.Formatters.Binary.ObjectMap.Create(String name, String[] memberNames, BinaryTypeEnum[] binaryTypeEnumA, Object[] typeInformationA, Int32[] memberAssemIds, ObjectReader objectReader, Int32 objectId, BinaryAssemblyInfo assemblyInfo, SizedArray assemIdToAssemblyTable) at System.Runtime.Serialization.Formatters.Binary._BinaryParser.ReadObjectWithMa pTyped(BinaryObjectWithMapTyped record) at System.Runtime.Serialization.Formatters.Binary._BinaryParser.ReadObjectWithMa pTyped(BinaryHeaderEnum binaryHeaderEnum) at System.Runtime.Serialization.Formatters.Binary.__BinaryParser.Run() at System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(Header Handler handler, __BinaryParser serParser, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage) at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Str eam serializationStream, HeaderHandler handler, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage) at System.Runtime.Remoting.Channels.CrossAppDomainSerializer.DeserializeObject(Me moryStream stm) at System.AppDomain.Deserialize(Byte[] blob) at System.AppDomain.UnmarshalObject(Byte[] blob) For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp." Using FUSLOGVW.exe (i.e., Assembly Binding Log Viewer), I can see the problem is that IIS attempts to find MyThirdPartyLibrary in directory C:\windows\system32\inetsrv. It refuses to look in the bin folder of the web app, where the DLL is actually located. Does anyone know what the problem is? Thanks, Calvin

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  • unformatted input to a std::string instead of c-string from binary file.

    - by posop
    ok i have this program working using c-strings. I am wondering if it is possible to read in blocks of unformatted text to a std::string? I toyed arround with if >> but this reads in line by line. I've been breaking my code and banging my head against the wall trying to use std::string, so I thought it was time to enlist the experts. Here's a working program you need to supply a file "a.txt" with some content to make it run. i tried to fool around with: in.read (const_cast<char *>(memblock.c_str()), read_size); but it was acting odd. I had to do std::cout << memblock.c_str() to get it to print. and memblock.clear() did not clear out the string. anyway, if you can think of a way to use STL I would greatly appreciate it. Here's my program using c-strings // What this program does now: copies a file to a new location byte by byte // What this program is going to do: get small blocks of a file and encrypt them #include <fstream> #include <iostream> #include <string> int main (int argc, char * argv[]) { int read_size = 16; int infile_size; std::ifstream in; std::ofstream out; char * memblock; int completed = 0; memblock = new char [read_size]; in.open ("a.txt", std::ios::in | std::ios::binary | std::ios::ate); if (in.is_open()) infile_size = in.tellg(); out.open("b.txt", std::ios::out | std::ios::trunc | std::ios::binary); in.seekg (0, std::ios::beg);// get to beginning of file while(!in.eof()) { completed = completed + read_size; if(completed < infile_size) { in.read (memblock, read_size); out.write (memblock, read_size); } // end if else // last run { delete[] memblock; memblock = new char [infile_size % read_size]; in.read (memblock, infile_size % read_size + 1); out.write (memblock, infile_size % read_size ); } // end else } // end while } // main if you see anything that would make this code better please feel free to let me know.

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  • How do you compile a resource into the binary?

    - by Wonderflonium
    How do you compile a resource into the binary in XCode? That way is doesn't show up inside the application bundle as a file and it's not subject to manipulation by a user (whether good-intentioned or bad). Is this even possible? I'm particularly interested about this in terms of iPhone apps. Any help is appreciated!

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  • How to convert binary, OCT, HEX to calculate in Java?

    - by user316751
    Write an application that inputs one number consisting of FIVE digits from the user, separates the number into its individual digits and prints the digits separated from one another by three spaces each. For example, if the user types in the number 12345, the program should print 1 2 3 4 5 The following screen dump of result is for your reference. Input a digit: 12345 Digits in 12345 = 1 2 3 4 5 How to convert binary, OCT, HEX to calculate the question?

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  • How do I make a Mach-O binary from an object file?

    - by Mike
    I have an object file, which I'd like to make into a Mach-O binary(I'm on Mac OS 10.6). Running ld source.o produces the following output: Undefined symbols: "_printf", referenced from: _main in source.o ld: symbol(s) not found for inferred architecture x86_64 How can I reference libSystem(or whatever library includes printf) using ld?

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  • How do I embed a binary within a Delphi executable and extract at runtime?

    - by Mick
    I'd like to embed an executable inside of my Delphi binary and extract it at runtime. The purpose of this is to ensure that a helper utility is always available on the system, without having to distribute multiple files. With Delphi 2007 I have used JvDataEmbedded, but I am building a console application and I want to know if anyone knows of another way to do it without having to add a hidden form for JvDataEmbedded. I am using Delphi 2010.

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  • How can I match a match a null byte (0x00) in the Visual Studio binary editor with a find using a re

    - by Paul K
    Open a file in the Visual Studio binary editor that contains a null byte (0x00), then use the Quick Find feature (Ctrl +F) to find null bytes. I would have thought I could use a regular expression such as \x00 to match null bytes but it doesn't work. Searching for any other hex value using this method works fine. Is this a VS bug, 'feature', or am I just missing something? Is there a work around?

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  • using LARGE_INTEGER gives me back error error C2679: '=' binary no operator found which takes a right-hand operand

    - by rekotc
    i have the following code: QueryPerformanceCounter(&timeStart); winMain::render(); //do stuff QueryPerformanceCounter(&timeEnd); numCounts = ( timeEnd.QuadPart - timeStart.QuadPart); All the 3 variables are declared as LARGE_INTEGER, the code should work since im following a book example, but i get: error C2679: '=' binary no operator found which takes a right-hand operand of type LONGLONG it might be '_LARGE_INTEGER &_LARGE_INTEGER::operator =(const _LARGE_INTEGER &)' 1 durante la ricerca di corrispondenza con l'elenco di argomenti '(LARGE_INTEGER, LONGLONG)'

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