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  • C Remove the first line from a text file without rewriting file

    - by Tom Van den Bon
    Hi, I've got a service which runs all the time and also keeps a log file. It basically adds new lines to the log file every few seconds. I'm written a small file which reads these lines and then parses them to various actions. The question I have is how can I delete the lines which I have already parsed from the log file without disrupting the writing of the log file by the service? Usually when I need to delete a line in a file then I open the original one and a temporary one and then I just write all the lines to the temp file except the original which I want to delete. Obviously this method will not word here. So how do I go about deleting them ?

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  • Any Alternate way for writing to a file other than ofstream

    - by Aditya
    Hi All, I am performing file operations (writeToFile) which fetches the data from a xml and writes into a output file(a1.txt). I am using MS Visual C++ 2008 and in windows XP. currently i am using this method of writing to output file.. 01.ofstreamhdr OutputFile; 02./* few other stmts / 03.hdrOutputFile.open(fileName, std::ios::out); 04. 05.hdrOutputFile << "#include \"commondata.h\""<< endl ; 06.hdrOutputFile << "#include \"Commonconfig.h\"" << endl ; 07.hdrOutputFile << "#include \"commontable.h\"" << endl << endl ; 08. hdrOutputFile << "#pragma pack(push,1)" << endl ; 09.hdrOutputFile << "typedef struct \n {" << endl ; 10./ simliar hdrOutputFiles statements... */.. I have around 250 lines to write.. Is any better way to perform this task. I want to reduce this hdrOutputFile and use a buffer to do this. Please guide me how to do that action. I mean, buff = "#include \"commontable.h\"" + "typedef struct \n {" + ....... hdrOutputFile << buff. is this way possible? Thanks Ramm

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  • Program crashes after trying to use a recently created file. C#

    - by Jason T.
    So here is my code if (!File.Exists(pathName)) { File.Create(pathName); } StreamWriter outputFile = new StreamWriter(pathName,true); But whenever I run the program the first time the path with file gets created. However once I get to the StreamWriter line my program crashes because it says my fie is in use by another process. Is there something I'm missing between the File.Create and the StreamWriter statements?

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  • searching within a compressed sorted fixed width file

    - by user275455
    Assume I have a regular compressed fixed width file that is sorted on one of the fields. Given that I know the length of the records, I can use lseek to implement a binary search to records with fields that match a given value without having to read the entire file. Now the difficulty is that the file is gzipped. Is it possible to do this without completely inflating the file? If not with gzip. is there any compression that supports this kind of behavior?

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  • How can I speed up line by line reading of an ASCII file? (C++)

    - by Jon
    Here's a bit of code that is a considerable bottleneck after doing some measuring: //----------------------------------------------------------------------------- // Construct dictionary hash set from dictionary file //----------------------------------------------------------------------------- void constructDictionary(unordered_set<string> &dict) { ifstream wordListFile; wordListFile.open("dictionary.txt"); string word; while( wordListFile >> word ) { if( !word.empty() ) { dict.insert(word); } } wordListFile.close(); } I'm reading in ~200,000 words and this takes about 240 ms on my machine. Is the use of ifstream here efficient? Can I do better? I'm reading about mmap() implementations but I'm not understanding them 100%. The input file is simply text strings with *nix line terminations.

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  • Read a file with 2048 bytes

    - by Suresh S
    Guys i have a file which has only one line. The file has no encoding it is a simple text file with single line. For every 2048 byte in a line , there is new record of 151 byte (totally 13*151 byte = 1945 records + 85 byte empty space). similarly for the next 2048 bytes. What is the best file i/o to use? i am thinking of reading 2048 bytes from file and storing it in an array . while (offset < fileLength &&(numRead=in.read(recordChunks, offset,alength)) >= 0) { } how can i get from the read statement only 2048 bytes at a time . i am getting IndexOutofBoundException.

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  • Get license file from a folder in C# project

    - by daft
    I have a license file that I need to access at runtime in order to create pdf-files. After I have created the in memory pdf, I need to call a method on that pdf to set the license, like this: pdf.SetLicense("pathToLicenseFileHere"); The license file is located in the same project as the.cs-file that creates the pdf, but is in a separate folder. I cannot get this simple thing to behave correctly, which makes me a bit sad, since it really shouldn't be that hard. :( I try to set the path like this: string path = @"\Resources\File.lic"; But it just isn't working out for me.

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  • best practices question: How to save a collection of images and a java object in a single file? File

    - by Richard
    Hi all, I am making a java program that has a collection of flash-card like objects. I store the objects in a jtree composed of defaultmutabletreenodes. Each node has a user object attached to it with has a few string/native data type parameters. However, i also want each of these objects to have an image (typical formats, jpg, png etc). I would like to be able to store all of this information, including the images and the tree data to the disk in a single file so the file can be transferred between users and the entire tree, including the images and parameters for each object, can be reconstructed. I had not approached a problem like this before so I was not sure what the best practices were. I found XLMEncoder (http://java.sun.com/j2se/1.4.2/docs/api/java/beans/XMLEncoder.html) to be a very effective way of storing my tree and the native data type information. However I couldn't figure out how to save the image data itself inside of the XML file, and I'm not sure it is possible since the data is binary (so restricted characters would be invalid). My next thought was to associate a hash string instead of an image within each user object, and then gzip together all of the images, with the hash strings as the names and the XMLencoded tree in the same compmressed file. That seemed really contrived though. Does anyone know a good approach for this type of issue? THanks! Thanks!

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  • StreamReader not working as expected

    - by Jon Preece
    Hi, I have written a simple utility that loops through all C# files in my project and updates the copyright text at the top. For example, a file may look like this; //Copyright My Company, © 2009-2010 The program should update the text to look like this; //Copyright My Company, © 2009-2010 However, the code I have written results in this; //Copyright My Company, � 2009-2011 Here is the code I am using; public bool ModifyFile(string filePath, List<string> targetText, string replacementText) { if (!File.Exists(filePath)) return false; if (targetText == null || targetText.Count == 0) return false; if (string.IsNullOrEmpty(replacementText)) return false; string modifiedFileContent = string.Empty; bool hasContentChanged = false; //Read in the file content using (StreamReader reader = File.OpenText(filePath)) { string file = reader.ReadToEnd(); //Replace any target text with the replacement text foreach (string text in targetText) modifiedFileContent = file.Replace(text, replacementText); if (!file.Equals(modifiedFileContent)) hasContentChanged = true; } //If we haven't modified the file, dont bother saving it if (!hasContentChanged) return false; //Write the modifications back to the file using (StreamWriter writer = new StreamWriter(filePath)) { writer.Write(modifiedFileContent); } return true; } Any help/suggestions are appreciated. Thanks!

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  • read chars from a file - c#

    - by Saskaaa
    How to read from a file array of numbers? I mean, how to read chars from a file? sorry for bad eng. upd: yes, i can :) just: "1 2 3 4 5 6 7 8" and etc. I just do not know how to read chars from a file.

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  • Python f.write() at beginning of file?

    - by kristus
    I'm doing it like this now, but i want it to write at the beginning of the file instead. f = open('out.txt', 'a') # or 'w'? f.write("string 1") f.write("string 2") f.write("string 3") f.close() so that the contenst of out.txt will be: string 3 string 2 string 1 and not (like this code does): string 1 string 2 string 3

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  • How to get proper alignment when printing to file

    - by user1067334
    I have this Structure the elements of which that I need to write in a text file struct Stage3ADisplay { int nSlot; char *Item; char *Type; int nIndex; unsigned char attributesMD[17]; //the last character is \0 unsigned char contentsMD[17]; //only for regular files - //the last character is \0 }; buffer = malloc(sizeof(Stage3ADisplayVar[nIterator]->nSlot) + sizeof(Stage3ADisplayVar[nIterator]->Item) + sizeof(Stage3ADisplayVar[nIterator]->Type) + sizeof(Stage3ADisplayVar[nIterator]->nIndex) + sizeof(Stage3ADisplayVar[nIterator]->attributesMD) + sizeof(Stage3ADisplayVar[nIterator]->contentsMD) + 1); sprintf (buffer,"%d %s %s %d %x %x",Stage3ADisplayVar[nIterator]->nSlot, Stage3ADisplayVar[nIterator]->Item,Stage3ADisplayVar[nIterator]->Type,Stage3ADisplayVar[nIterator]->nIndex,Stage3ADisplayVar[nIterator]->attributesMD,Stage3ADisplayVar[nIterator]->contentsMD); How do I make sure the rows in the file are properly aligned. Thank you.

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  • File Operations in Android NDK

    - by EnderX
    I am using the Android NDK to make an application primarily in C for performance reasons, but it appears that file operations such as fopen do not work correctly in Android. Whenever I try to use these functions, the application crashes. How do I create/write to a file with the Android NDK?

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  • FileNotFound exception

    - by Pratik
    I am trying to read a file in a servlet. I am using eclipse IDE. I get a FileNotFoundException if I provide relative file name. List<String> ls=new ArrayList<String>(); Scanner input = new Scanner(new File("Input.txt")); while(input.hasNextLine()) { ls.add(input.nextLine()); } The same code works if I put the absolute path like this: Scanner input = new Scanner(new File("F:/Spring and other stuff/AjaxDemo/src/com/pdd/ajax/Input.txt")); The Java file and text file are there in the same folder. Does it searches text file in some other folder ?

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  • [NSData dataWithContentsOfFile:path] doesn't work

    - by Felics
    Hello, when I have the fallowing code to read a binary file: NSString* file = [NSString stringWithUTF8String:fileName]; NSString* filePath = resource ? [[NSBundle mainBundle] pathForResource:file ofType:nil] : [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent: file]; NSData* fileData = [NSData dataWithContentsOfFile:filePath]; Where "fileName" and resource are load function parameters. "resource" is used to know if the file is located in application bundle or in Documents. Sometimes this code works well and sometimes it doesn't. As far I saw this problem is random. I can run the code 10 times in a row and it works fine and after that it gives me nil data without any modification. Does anybody knows what could be the problem? Could it be related with file extension or file name? Thank you. PS: I use this code on iPhone Simulator and the file exists in application bundle.

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  • How do I open a file in such a way that if the file doesn't exist it will be created and opened automatically?

    - by snakile
    Here's how I open a file for writing+ : if( fopen_s( &f, fileName, "w+" ) !=0 ) { printf("Open file failed\n"); return; } fprintf_s(f, "content"); If the file doesn't exist the open operation fails. What's the right way to fopen if I want to create the file automatically if the file doesn't already exist? EDIT: If the file does exist, I would like fprintf to overwrite the file, not to append to it.

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  • Python text file processing speed issues

    - by Anonymouslemming
    Hi all, I'm having a problem with processing a largeish file in Python. All I'm doing is f = gzip.open(pathToLog, 'r') for line in f: counter = counter + 1 if (counter % 1000000 == 0): print counter f.close This takes around 10m25s just to open the file, read the lines and increment this counter. In perl, dealing with the same file and doing quite a bit more (some regular expression stuff), the whole process takes around 1m17s. Perl Code: open(LOG, "/bin/zcat $logfile |") or die "Cannot read $logfile: $!\n"; while (<LOG>) { if (m/.*\[svc-\w+\].*login result: Successful\.$/) { $_ =~ s/some regex here/$1,$2,$3,$4/; push @an_array, $_ } } close LOG; Can anyone advise what I can do to make the Python solution run at a similar speed to the Perl solution? I've tried just uncompressing the file and dealing with it using open instead of gzip.open, but that made a very small difference to the overall time.

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  • download large files using servlet

    - by niks
    I am using Apache Tomcat Server 6 and Java 1.6 and am trying to write large mp3 files to the ServletOutputStream for a user to download. Files are ranging from a 50-750MB at the moment. The smaller files aren't causing too much of a problem but with the larger files it and getting socket exception broken pipe. File fileMp3 = new File(objDownloadSong.getStrSongFolder() + "/" + strSongIdName); FileInputStream fis = new FileInputStream(fileMp3); response.setContentType("audio/mpeg"); response.setHeader("Content-Disposition", "attachment; filename=\"" + strSongName + ".mp3\";"); response.setContentLength((int) fileMp3.length()); OutputStream os = response.getOutputStream(); try { int byteRead = 0; while ((byteRead = fis.read()) != -1) { os.write(byteRead); } os.flush(); } catch (Exception excp) { downloadComplete = "-1"; excp.printStackTrace(); } finally { os.close(); fis.close(); }

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  • write cache and write sequence order

    - by excanoe
    ok, here i have some weird question: let say we have some binary file (.log), and sequence of write operations, for example log1, log2, log3 and each has some block size n (raw data). question: can I be sure that log1,log2 and log3 sequences can be written in the correct order in ONE file, even if i have few cache levels (disk hardware and os level)? update very interested in what will be with records order (not with records) if we have software or hardware failure (reboot or another reason). update there can be some percent of write failures, but main question is: will write order stay correct?

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  • Unable to write to a text file

    - by chrissygormley
    Hello, I am running some tests and need to write to a file. When I run the test's the open = (file, 'r+') does not write to the file. The test script is below: class GetDetailsIP(TestGet): def runTest(self): self.category = ['PTZ'] try: # This run's and return's a value result = self.client.service.Get(self.category) mylogfile = open("test.txt", "r+") print >>mylogfile, result result = ("".join(mylogfile.readlines()[2])) result = str(result.split(':')[1].lstrip("//").split("/")[0]) mylogfile.close() except suds.WebFault, e: assert False except Exception, e: pass finally: if 'result' in locals(): self.assertEquals(result, self.camera_ip) else: assert False When this test run's, no value has been entered into the text file and a value is returned in the variable result. I havw also tried mylogfile.write(result). If the file does not exist is claim's the file does not exist and doesn't create one. Could this be a permission problem where python is not allowed to create a file? I have made sure that all other read's to this file are closed so I the file should not be locked. Can anyone offer any suggestion why this is happening? Thanks

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  • Saving MP3 playlist to file

    - by Northernen
    Hello. I am making my own crude MP3 player, and I now have a JList with which I have populated a number of files in the form of MP3 objects (displayed on frame using DefaultListModel). I would now like to have the oppurtunity to save this JList to a file on disk. How would I go about doing this? I'm very new with programming and Java, so help is greatly appreciated.

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  • Read char from txt file in C++

    - by Jack in the Box
    I have a program that will read the number of rows and columns from a txt file. Also, the program has to read the contents of a 2D array from the same file. Here is the txt file 8 20 * * *** *** 8 and 20 are the number of rows and columns respectively. The spaces and asterisks are the contents of the array, Array[8][20] For example, Array[0][1] = '*' I did make the program reading 8 and 20 as follow: ifstream myFile; myFile.open("life.txt"); if(!myFile) { cout << endl << "Failed to open file"; return 1; } myFile >> rows >> cols; myFile.close(); grid = new char*[rows]; for (int i = 0; i < rows; i++) { grid[i] = new char[cols]; } Now, how to assign the spaces and the asterisks to to the fields in the array? I hope you got the point.

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