file-io

问题 I have a windows service that writes out log file entries to an XML log file. I maintain a handle to the log file while the service is operational, and close, flush and dispose of it when the service is stopped. The file write operations are by the service only, and I have the filestream open in FileAccess.ReadWrite while sharing is set to FileShare.Read. I would like to be able to open and view this file with an XmlRead() call by another application, but I get an error stating the file is

问题 The distributed file systems which like Google File System and Hadoop doesn't support random I/O. (It can't modify the file which were written before. Only writing and appending is possible.) Why did they design file system like this? What are the important advantages of the design? P.S I know Hadoop will support modifing the data which were written. But they said, it's performance will very not good. Why? 回答1: Hadoop distributes and replicates files. Since the files are replicated, any write

问题 The distributed file systems which like Google File System and Hadoop doesn't support random I/O. (It can't modify the file which were written before. Only writing and appending is possible.) Why did they design file system like this? What are the important advantages of the design? P.S I know Hadoop will support modifing the data which were written. But they said, it's performance will very not good. Why? 回答1: Hadoop distributes and replicates files. Since the files are replicated, any write

问题 My problem is: select indicates that there is data to be read, I want to read whatever is there, I do not want to wait for a max amount to be present. if max <= 0 then read waits until EOF is encountered, if max >0 read blocks until max bytes can be read. I don't want this, I want to read whatever amount made select put it in the "ready for reading" list. read(1) isn't practical because this will involve A LOT of calls to read. BUT it mustn't block. Is there a way to find out the amount

问题 This question already has answers here : Is fopen() limited by the filesystem? (4 answers) Closed 6 years ago . I have a set of files that I want to concatenate (each represents a part from a multi-part download). Each splitted file is about 250MiB in size, and I have a variable number of them. My concatenation logic is straight-forward: if (is_resource($handle = fopen($output, 'xb')) === true) { foreach ($parts as $part) { if (is_resource($part = fopen($part, 'rb')) === true) { while (feof(

问题 So... I used to think that when you accessed a file but specified the name without a path (CAISLog.csv in my case) that .NET would expect the file to reside at the same path as the running .exe. This works when I'm stepping through a solution (C# .NET2.* VS2K5) but when I run the app in normal mode (Started by a Websphere MQ Trigger monitor & running in the background as a network service) instead of accessing the file at the path where the .exe is it's being looked for at C:\WINDOWS\system32

问题 I'm using boost 1.50 with VS2010, reading using a Windows file HANDLE (which seems to be relatively uncommon compared to asio use with sockets). Problem The handle_read callback gets to line 8 and returns the first bit with all of line 1 appended; further callbacks cycle through from line 2 again, ad nauseum: open a short text file (below) get expected handle_read callbacks with correct content for lines 1 through 7 the next callback has a longer-than-expected bytes-read length parameter

问题 I have a file: a 0 0 b 1 1 c 3 4 d 5 6 Using istringstream, I need to get a, then b, then c, etc. But I don't know how to do it because there are no good examples online or in my book. Code so far: ifstream file; file.open("file.txt"); string line; getline(file,line); istringstream iss(line); iss >> id; getline(file,line); iss >> id; This prints "a" for id both times. I don't know how to use istringstream obviously and I HAVE to use istringstream. Please help! 回答1: ifstream file; file.open(

问题 I'd like to ask a question then follow it up with my own answer, but also see what answers other people have. We have two large files which we'd like to read from two separate threads concurrently. One thread will sequentially read fileA while the other thread will sequentially read fileB. There is no locking or communication between the threads, both are sequentially reading as fast as they can, and both are immediately discarding the data they read. Our experience with this setup on Windows

问题 I have input files containing data in the following format. 65910/A 22 9 4 2 9 10 4 1 2 5 2 0 4 1 1 0 65910/T 14 7 0 4 8 4 0 2 1 2 0 0 1 1 1 1 . . . I need to take the input where the first line is a combination of %d and %c with a / in between and the next four line as a 4x4 integer matrix. I need to perform some work on the matrix and then identify them with the header information. How can I take this input format in MATLAB? 回答1: Since your file contains data that may be considered