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  • How can I insert or remove bytes from the middle of a large file in .NET

    - by Eric
    Is it possible to efficiently insert or remove bytes from the middle of a large file, and if so how? Or am I stuck rewriting the entire file after the point where the data was inserted or removed? [A lot of Bytes][Unwanted Bytes][A lot of Bytes] - > [A lot of Bytes][A lot of Bytes] or [A lot of Bytes][A lot of Bytes] - > [A loto f Bytes][New Inserted Bytes][A lot of Bytes]

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  • Java: Send BufferedImage through Socket with a low bitdepth

    - by Martijn Courteaux
    Hi, The title says enough I think. I have a full quality BufferedImage and I want to send it through an OutputStream with a low bitdepth. I don't want an algorithm to change pixel by pixel the quality, so it is still a full-quality. So, the goal is to write the image (with the full resolution) through the OuputStream with a very small size. Thanks, Martijn

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  • Android: writing a file to sdcard

    - by Sumit M Asok
    I'm trying to write a file from an Http post reply to a file on the sdcard. Everything works fine until the byte array of data is retrieved. I've tried setting WRITE_EXTERNAL_STORAGE permission in the manifest and tried many different combinations of tutorials I found on the net. All I could find was using the openFileOutput("",MODE_WORLD_READABLE) method, of the activity but how my app writes file is by using a thread. Specifically, a thread is invoked from another thread when a file has to be written, so giving an activity object didn't work even though I tried it. The app has come a long way and I cannot change how the app is currently written. Please, someone help me? CODE: File file = new File(bgdmanip.savLocation); FileOutputStream filecon = null; filecon = new FileOutputStream(file); // bgdmanip.savLocation holds the whole files path byte[] myByte; myByte = Base64Coder.decode(seReply); Log.d("myBytes", String.valueOf(myByte)); bos.write(myByte); filecon.write(myByte); myvals = x * 11024; seReply is a string reply from HttpPost response. the second set of code is looped with reference to x. the file is created but remains 0 bytes

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  • How can I walk through two files simultaneously in Perl?

    - by Alex Reynolds
    I have two text files that contain columnar data of the variety position-value, sorted by position. Here is an example of the first file (file A): 100 1 101 1 102 0 103 2 104 1 ... Here is an example of the second file (B): 20 0 21 0 ... 100 2 101 1 192 3 193 1 ... Instead of reading one of the two files into a hash table, which is prohibitive due to memory constraints, what I would like to do is walk through two files simultaneously, in a stepwise fashion. What this means is that I would like to stream through lines of either A or B and compare position values. If the two positions are equal, then I perform a calculation on the values associated with that position. Otherwise, if the positions are not equal, I move through lines of file A or file B until the positions are equal (when I again perform my calculation) or I reach EOF of both files. Is there a way to do this in Perl?

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  • C# File Exception: cannot access the file because it is being used by another process

    - by Lirik
    I'm trying to download a file from the web and save it locally, but I get an exception: C# The process cannot access the file 'blah' because it is being used by another process. This is my code: File.Create("data.csv"); // create the file request = (HttpWebRequest)WebRequest.CreateDefault(new Uri(url)); request.Timeout = 30000; response = (HttpWebResponse)request.GetResponse(); using (Stream file = File.OpenWrite("data.csv"), // <-- Exception here input = response.GetResponseStream()) { // Save the file using Jon Skeet's CopyStream method CopyStream(input, file); } I've seen numerous other questions with the same exception, but none of them seem to apply here. Any help?

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  • Is it possible to stream a file to and from servers without holding the data in ram?

    - by Chris Denman
    Hi everyone! PHP question (new to PHP after 10 years of Perl, arrggghhh!). I have a 100mb file that I want to send to another server. I have managed to read the file in and "post" it without curl (cannot use curl for this app). Everything is working fine on smaller files. However, with the larger files, PHP complains about not being able to allocate memory. Is there a way to open a file, line by line, and send it as a post ALSO line by line? This way nothing is held in ram thus preventing my errors and getting around strict limitations. Chris

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  • .NET: IOException for permissions when creating new file?

    - by Rosarch
    I am trying to create a new file and write XML to it: FileStream output = File.Create(Path.Combine(PATH_TO_DATA_DIR, fileName)); The argument evaluates to: C:\path\to\Data\test.xml The exception is: The process cannot access the file 'C:\path\to\Data\test.xml' because it is being used by another process. What am I doing wrong here? UPDATE: This code throws the same exception: StreamWriter writer = new StreamWriter(Path.Combine(PATH_TO_DATA_DIR, fileName)); UPDATE 2: The file I am trying to create does not exist in the file system. So how can be it in use?

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  • lseek/write suddenly returns -1 with errno = 9 (Bad file descriptor)

    - by Ger Teunis
    My application uses lseek to seek the desired position to write data. The file is opened using open() command successfully and my application was able to use lseek and wite lots of times. At a given time, for some users and not easily reproducible the lseek returns -1 with an errno of 9. File is not closed before this and the filehandle (int) isn't reset. After this an other file is created open is okay again and lseek and write works again. To make it even worse, this user tried the complete sequence again and all was well. So my question is, can the OS close the file handle for me for some reason? What could cause this? A file indexer or file scanner of some sort? What is the best way to solve this; is this pseudo code the best solution? (never mind the code layout, will create functions for it) int fd=open(...); if (fd>-1) { long result = lseek(fd,....); if (result == -1 && errno==9) { close(fd..); //make sure we try to close nicely fd=open(...); result = lseek(fd,....); } } Anybody experience with something similar? Summary: file seek and write works okay for a given fd and suddenly gives back errno=9 without a reason.

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  • Possible to open a text file in a MYSQL stored procedure?

    - by futureelite7
    Is it possible to open and read from a text file in a MYSQL stored procedure? I have a text file with a list of about 50k telephone numbers, and want to write a stored procedure that will open the file, read the 50k lines and store it as rows in a table. I cannot load the file directly using LOAD IN FILE as the table has additional columns that I have to set. Thanks!

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  • According to MSDN ReadFile() Win32 function may incorrectly report read operation completion. When?

    - by Martin Dobšík
    The MSDN states in its description of ReadFile() function (http://msdn.microsoft.com/en-us/library/aa365467%28VS.85%29.aspx): “If hFile is opened with FILE_FLAG_OVERLAPPED, the lpOverlapped parameter must point to a valid and unique OVERLAPPED structure, otherwise the function can incorrectly report that the read operation is complete.” I have some applications that are violating the above recommendation and I would like to know the severity of the problem. I mean the program uses named pipe that has been created with FILE_FLAG_OVERLAPPED, but it reads from it using the following call: ReadFile(handle, &buf, n, &n_read, NULL); That means it passes NULL as the lpOverlapped parameter. That call should not work correctly in some circumstances according to documentation. I have spent a lot of time trying to reproduce the problem, but I was unable to! I always got all data in right place at right time. I was testing only Named Pipes though. Would anybody know when can I expect that ReadFile() will incorrectly return and report successful completion even the data are not yet in the buffer? What would have to happen in order to reproduce the problem? Does it happen with files, pipes, sockets, consoles, or other devices? Do I have to use particular version of OS? Or particular version of reading (like register the handle to I/O completion port)? Or particular synchronization of reading and writing processes/threads? Or when would that fail? It works for me :/ Please help! With regards Martin

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  • C# .Net file in use issue

    - by Dan
    I'm having an issue opening files that have recently been closed by the .Net framework. Basically, what happens is the following: -Read in an XML file using DataSet.ReadXml() -Make some changes to the data -Write out the XML file using DataSet.WriteXml() -Copy the XML file to a new location using File.Copy -FTP the file using a custom control This sequence can intermittently fail either after the WriteXML or the File.Copy with a file in use exception. I'm guessing it could be the Windows write cache not flushing right away. Can anyone confirm that this could be causing my issue? Any solutions to suggest? Thanks, Dan

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  • C file read leaves garbage characters

    - by KJ
    Hi. I'm trying to read the contents of a file into my program but I keep occasionally getting garbage characters at the end of the buffers. I haven't been using C a lot (rather I've been using C++) but I assume it has something to do with streams. I don't really know what to do though. I'm using MinGW. Here is the code (this gives me garbage at the end of the second read): include include char* filetobuf(char *file) { FILE *fptr; long length; char *buf; fptr = fopen(file, "r"); /* Open file for reading */ if (!fptr) /* Return NULL on failure */ return NULL; fseek(fptr, 0, SEEK_END); /* Seek to the end of the file */ length = ftell(fptr); /* Find out how many bytes into the file we are */ buf = (char*)malloc(length+1); /* Allocate a buffer for the entire length of the file and a null terminator */ fseek(fptr, 0, SEEK_SET); /* Go back to the beginning of the file */ fread(buf, length, 1, fptr); /* Read the contents of the file in to the buffer */ fclose(fptr); /* Close the file */ buf[length] = 0; /* Null terminator */ return buf; /* Return the buffer */ } int main() { char* vs; char* fs; vs = filetobuf("testshader.vs"); fs = filetobuf("testshader.fs"); printf("%s\n\n\n%s", vs, fs); free(vs); free(fs); return 0; } The filetobuf function is from this example http://www.opengl.org/wiki/Tutorial2:_VAOs,_VBOs,_Vertex_and_Fragment_Shaders_%28C_/_SDL%29. It seems right to me though. So anyway, what's up with that?

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  • C# double-quoted path name being escaped when read from file

    - by KrisTrip
    I am trying to read in a text input file that contains a list of filenames (one per line). However, I am running into an issue if the user double-quotes the path (because it has a space in it). For example, a normal input file might have: C:\test\test.tiff C:\test\anothertest.tiff C:\test\lasttest.tiff These get read in fine by my code ("C:\\test\\test.tiff" etc) However, if I have the following input file: "C:\test with spaces\test.tiff" "C:\test with spaces\anothertest.tiff" "C:\test with spaces\lasttest.tiff" These get read in double-quotes and all ("\"C:\\test with spaces\\test.tiff\"" etc). This becomes a problem when I try to open the files (I understandably get invalid character exceptions). My question is, how do I fix this? I want to allow users to input quoted strings and handle them correctly. My first impression was to just write a little method that strips off beginning or ending quotes, but I thought there might be a better way.

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  • Reading Binary file in C

    - by darkie15
    Hi All, I am having following issue with reading binary file in C. I have read the first 8 bytes of a binary file. Now I need to start reading from the 9th byte. Following is the code: fseek(inputFile, 2*sizeof(int), SEEK_SET); However, when I print the contents of the array where I store the retrieved values, it still shows me the first 8 bytes which is not what I need. Can anyone please help me out with this? Regards, darkie

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  • Blackberry read local properties file in project

    - by Dachmt
    Hi, I have a config.properties file at the root of my blackberry project (same place as Blackberry_App_Descriptor.xml file), and I try to access the file to read and write into it. See below my class: public class Configuration { private String file; private String fileName; public Configuration(String pathToFile) { this.fileName = pathToFile; try { // Try to load the file and read it System.out.println("---------- Start to read the file"); file = readFile(fileName); System.out.println("---------- Property file:"); System.out.println(file); } catch (Exception e) { System.out.println("---------- Error reading file"); System.out.println(e.getMessage()); } } /** * Read a file and return it in a String * @param fName * @return */ private String readFile(String fName) { String properties = null; try { System.out.println("---------- Opening the file"); //to actually retrieve the resource prefix the name of the file with a "/" InputStream is = this.getClass().getResourceAsStream(fName); //we now have an input stream. Create a reader and read out //each character in the stream. System.out.println("---------- Input stream"); InputStreamReader isr = new InputStreamReader(is); char c; System.out.println("---------- Append string now"); while ((c = (char)isr.read()) != -1) { properties += c; } } catch (Exception e) { } return properties; } } I call my class constructor like this: Configuration config = new Configuration("/config.properties"); So in my class, "file" should have all the content of the config.properties file, and the fileName should have this value "/config.properties". But the "name" is null because the file cannot be found... I know this is the path of the file which should be different, but I don't know what i can change... The class is in the package com.mycompany.blackberry.utils Thank you!

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  • c#: how to read parts of a file? (DICOM)

    - by Xaisoft
    I would like to read a DICOM file in C#. I don't want to do anything fancy, I just for now would like to know how to read in the elements, but first I would actually like to know how to read the header to see if is a valid DICOM file. It consists of Binary Data Elements. The first 128 bytes are unused (set to zero), followed by the string 'DICM'. This is followed by header information, which is organized into groups. A sample DICOM header First 128 bytes: unused DICOM format. Followed by the characters 'D','I','C','M' Followed by extra header information such as: 0002,0000, File Meta Elements Groups Len: 132 0002,0001, File Meta Info Version: 256 0002,0010, Transfer Syntax UID: 1.2.840.10008.1.2.1. 0008,0000, Identifying Group Length: 152 0008,0060, Modality: MR 0008,0070, Manufacturer: MRIcro In the above example, the header is organized into groups. The group 0002 hex is the file meta information group which contains 3 elements: one defines the group length, one stores the file version and the their stores the transfer syntax. Questions How to I read the header file and verify if it is a DICOM file by checking for the 'D','I','C','M' characters after the 128 byte preamble? How do I continue to parse the file reading the other parts of the data?

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  • Parse values from a text file in C

    - by Mohit Deshpande
    Say I have written to a text file in this format: key1/value1 key2/value2 akey/withavalue anotherkey/withanothervalue I have a linked list like: struct Node { char *key; char *value; struct Node *next; }; to hold the values. How would I read key1 and value1? I was thinking of putting line by line in a buffer and using strtok(buffer, '/'). Would that work? What other ways could work, maybe a bit faster or less prone to error? Please include a code sample if you can!

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  • Get PocketC File Handle Int?

    - by Nathan Campos
    I'm now taking a look at the PocketC powerful tool, but there is an fileopen function, that generates a integer called filehandle, that is used for most of the File I/O operations of PocketC, than I want to know how to discover the int filehandle from the function? Here is my example function that I'm using at my program: fileopen("\test.txt", 0, 0x00000000); Description of int filehandle: Integer used for file operations, used as a pointer to the fileopen instruction.

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  • fwrite = unblocking ?

    - by John Michaels
    Since you can't be sure that what you write with fwrite has been written (god thats an awesome sentence) before you call fflush can i consider fwrite a nonblocking write?? And if not, why not and what are my alternatives?

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  • kernelHow to read/write files within kernel module?

    - by Methos
    I know all the discussions about why one should not read/write files from kernel, instead how to use /proc or netlink to do that. I want to read/write anyway. I have also read http://www.linuxjournal.com/article/8110 However, problem is 2.6.30 does not export sys_read(). Rather its wrapped in SYSCALL_DEFINE3. So if I use that in my module, I get following warnings: WARNING: "sys_read" [xxx.ko] undefined! WARNING: "sys_open" [xxx.ko] undefined! Obviously insmod cannot load the module because linking does not happen correctly. Questions: How to read/write within kernel after 2.6.22 (where sys_read()/sys_open() are not exported)? In general, how to use system calls wrapped in macro SYSCALL_DEFINEn() from within the kernel?

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  • WML And Downloads

    - by Nathan Campos
    I'm now playing with WML and WMLScript, but I'm doing a site that will have some content to download(some txt, doc, bmp, mpg, avi and jpg files), but some of my friends(that never developed in this language, just used the technology on the beginning) said that it's impossible. Then here are my questions: It's possible? How to do it? Remember that I'm using PHP combined with WML.

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  • Prevent Windows Explorer from interfering with Directory operations.

    - by Bruno Martinez
    Sometimes, no "foo" directory is left after running this code: string folder = Path.Combine(Path.GetTempPath(), "foo"); if (!Directory.Exists(folder)) Directory.CreateDirectory(folder); Process.Start(@"c:\windows\explorer.exe", folder); Thread.Sleep(TimeSpan.FromSeconds(5)); Directory.Delete(folder, false); Directory.CreateDirectory(folder); It seems Windows Explorer keeps a reference to the folder, so the last CreateDirectory has nothing to do, but then the original folder is deleted. How can I fix the code?

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