Questions tagged [buffer]
A buffer is an area of memory set aside for temporary storage of data while it is being moved from one place to another. This is typically done to speed up processes with significant latency, such as writing to a disk, printer or other physical device. The output is ready to be sent to the device before the device is ready to accept it, so it is moved to the buffer so that the sending program does not have to continue waiting.
buffer
7,115
questions
697
votes
16
answers
367k
views
How can I clear previous output in Terminal in Mac OS X?
I know the clear command that 'clears' the current screen, but it does this just by printing lots of newlines - the cleared contents just get scrolled up.
Is there a way to completely wipe all ...
- 85.2k
589
votes
10
answers
368k
views
How do I close a single buffer (out of many) in Vim?
I open several files in Vim by, for example, running
vim a/*.php
which opens 23 files.
I then make my edit and run the following twice
:q
which closes all my buffers.
How can you close only one ...
- 138k
241
votes
9
answers
124k
views
What does it mean by buffer?
I see the word "BUFFER" everywhere, but I am unable to grasp what it exactly is.
Would anybody please explain what is buffer in layman's language?
When is it used?
How is it used?
- 36.6k
228
votes
14
answers
306k
views
Convert a binary NodeJS Buffer to JavaScript ArrayBuffer
How can I convert a NodeJS binary buffer into a JavaScript ArrayBuffer?
- 3,212
225
votes
5
answers
259k
views
What is the use of ByteBuffer in Java? [closed]
What are example applications for a ByteBuffer in Java? Please list any example scenarios where this is used.
- 2,651
204
votes
14
answers
257k
views
What is the difference between buffer and cache memory in Linux?
To me it's not clear what's the difference between the two Linux memory concepts : buffer and cache. I've read through this post and it seems to me that the difference between them is the expiration ...
- 8,285
198
votes
12
answers
314k
views
Save Screen (program) output to a file
I need to save the whole output of Screen to a file to check later all the content.
The reason is that I'm dumping a flash memory through a serial port, using Screen to interface with it. I would like ...
- 2,859
186
votes
3
answers
289k
views
Convert a JSON Object to Buffer and Buffer to JSON Object back
I have a JSON object and I'm converting it to a Buffer and doing some process here. Later I want to convert the same buffer data to convert to valid JSON object.
I'm working on Node V6.9.1
Below is ...
- 1,863
180
votes
10
answers
136k
views
How do you determine the ideal buffer size when using FileInputStream?
I have a method that creates a MessageDigest (a hash) from a file, and I need to do this to a lot of files (>= 100,000). How big should I make the buffer used to read from the files to maximize ...
- 3,457
179
votes
9
answers
229k
views
Converting a Buffer into a ReadableStream in Node.js
I have a library that takes as input a ReadableStream, but my input is just a base64 format image. I could convert the data I have in a Buffer like so:
var img = new Buffer(img_string, 'base64');
But ...
- 21.1k
175
votes
7
answers
86k
views
Force line-buffering of stdout in a pipeline
Usually, stdout is line-buffered. In other words, as long as your printf argument ends with a newline, you can expect the line to be printed instantly. This does not appear to hold when using a pipe ...
- 33k
160
votes
6
answers
145k
views
How large should my recv buffer be when calling recv in the socket library
I have a few questions about the socket library in C. Here is a snippet of code I'll refer to in my questions.
char recv_buffer[3000];
recv(socket, recv_buffer, 3000, 0);
How do I decide how big to ...
- 6,489
155
votes
8
answers
444k
views
Reading and writing binary file
I'm trying to write code to read a binary file into a buffer, then write the buffer to another file. I have the following code, but the buffer only stores a couple of ASCII characters from the first ...
- 4,179
153
votes
6
answers
796k
views
C char array initialization: what happens if there are less characters in the string literal than the array size?
I'm not sure what will be in the char array after initialization in the following ways.
1.char buf[10] = "";
2. char buf[10] = " ";
3. char buf[10] = "a";
For case 2, I think buf[0] should be '...
- 2,345
148
votes
8
answers
25k
views
How to delete multiple buffers in Vim?
Assuming I have multiple files opened as buffers in Vim. The files have *.cpp, *.h and some are *.xml. I want to close all the XML files with :bd *.xml. However, Vim does not allow this (E93: More ...
- 4,357
141
votes
10
answers
172k
views
Clearing a string buffer/builder after loop
How do you clear the string buffer in Java after a loop so the next iteration uses a clear string buffer?
- 1,419
136
votes
3
answers
78k
views
What does flushing the buffer mean?
I am learning C++ and I found something that I can't understand:
Output buffers can be explicitly flushed to force the buffer to be
written. By default, reading cin flushes cout; cout is also ...
- 4,019
133
votes
2
answers
151k
views
How to display nodejs raw Buffer data as Hex string
The following code uses SerialPort module to listen to data from a bluetooth connection.
I am expecting to see a stream of data in Hexadecimal format printed in console. But the console just shows ...
- 3,867
132
votes
6
answers
78k
views
What exactly is the point of memoryview in Python?
Checking the documentation on memoryview:
memoryview objects allow Python code to access the internal data of an
object that supports the buffer protocol without copying.
class memoryview(...
- 8,007
124
votes
11
answers
33k
views
Replace word with contents of paste buffer?
I need to do a bunch of word replacements in a file and want to do it with a vi command, not an EX command such as :%s///g.
I know that this is the typical way one replaces the word at the current ...
- 1,753
124
votes
4
answers
40k
views
Diff two tabs in Vim
Scenario: I have opened Vim and pasted some text. I open a second tab with :tabe and paste some other text in there.
Goal: I would like a third tab with a output equivalent to writing both texts to ...
- 17.6k
124
votes
5
answers
27k
views
Refresh all files in buffer from disk in vim
The command to refresh a file from version on disk is :e!
How can I do the same for all files in the buffer?
Background: I need that because I am using git with multiple branches with one vim open ...
- 2,103
117
votes
20
answers
510k
views
How can I clear an input buffer in C?
I have the following program:
int main(int argc, char *argv[])
{
char ch1, ch2;
printf("Input the first character:"); // Line 1
scanf("%c", &ch1);
printf("...
- 13.5k
116
votes
5
answers
43k
views
Intellij IDEA with ideavim. Cannot copy text from another source
I tried to copy text from IDEA with ideavim plugin, using default vim keybindings (y). But this text isn't copied in global buffer and i can paste it only in IDEA.
How can I use copied piece of text ...
- 1,235
108
votes
4
answers
147k
views
How to append binary data to a buffer in node.js
I have a buffer with some binary data:
var b = new Buffer ([0x00, 0x01, 0x02]);
and I want to append 0x03.
How can I append more binary data? I'm searching in the documentation but for appending ...
- 18.4k
102
votes
5
answers
81k
views
What exactly does "Stream" and "Buffer" mean in Java I/O?
I just learned about input/output using BufferedReader.
I wanted to know what exactly are the meanings of the term Stream and Buffer?
Also what does this line of code serves us:
BufferedReader br=...
- 1,563
98
votes
16
answers
61k
views
How do you prefer to switch between buffers in Vim?
I've tried MiniBufExplorer, but I usually end up with several windows showing it or close it altogether. What I'd like is something like LustyJuggler with incremental search, the way I switch between ...
- 170k
94
votes
9
answers
140k
views
Ring Buffer in Java
I have a streaming time series, of which I am interested in keeping the last 4 elements, which means I want to be able to pop the first, and add to the end. Essentially what I need is a ring buffer.
...
- 941
93
votes
3
answers
50k
views
When to use byte array & when byte buffer?
What is the difference between a byte array & byte buffer ?
Also, in what situations should one be preferred over the other?
[my usecase is for a web application being developed in java].
- 26.3k
91
votes
2
answers
21k
views
What is the recommended way of allocating memory for a typed memory view?
The Cython documentation on typed memory views list three ways of assigning to a typed memory view:
from a raw C pointer,
from a np.ndarray and
from a cython.view.array.
Assume that I don't have ...
- 13.5k
89
votes
6
answers
11k
views
Why do I need std::get_temporary_buffer?
For what purpose I should use std::get_temporary_buffer? Standard says the following:
Obtains a pointer to storage sufficient to store up to n adjacent T objects.
I thought that the buffer will be ...
- 98.8k
86
votes
5
answers
223k
views
How to find the socket buffer size of linux
What's the default socket buffer size of linux? Is there any command to see it?
- 197k
85
votes
2
answers
88k
views
Node.js convert hexadecimal number to byteArray
I want to send a raw buffer using bluetooth connection. The content is a hex number. Currently I split the number manually to an byte array. Is there any function that can help me convert the number ...
- 3,867
84
votes
4
answers
152k
views
Java - Convert int to Byte Array of 4 Bytes? [duplicate]
Possible Duplicate:
Convert integer into byte array (Java)
I need to store the length of a buffer, in a byte array 4 bytes large.
Pseudo code:
private byte[] convertLengthToByte(byte[] myBuffer)...
- 11.5k
84
votes
1
answer
233k
views
Flushing buffers in C
Should fflush() not be used to flush a buffer even if it is an output stream?
What is it useful for? How do we flush a buffer in general?
- 3,171
83
votes
4
answers
86k
views
C# FileStream : Optimal buffer size for writing large files?
Suppose I'm writing a couple of files to disk, between 2MB and 5GB.
What are sensible buffer values for the FileStream ?
Is it sensible to work with buffersizes of several megabytes, or should I ...
- 1,896
80
votes
3
answers
37k
views
std::fstream buffering vs manual buffering (why 10x gain with manual buffering)?
I have tested two writing configurations:
Fstream buffering:
// Initialization
const unsigned int length = 8192;
char buffer[length];
std::ofstream stream;
stream.rdbuf()->pubsetbuf(buffer, ...
- 59.6k
76
votes
4
answers
72k
views
Byte array of unknown length in java
I am constructing an array of bytes in java and I don't know how long the array will be.
I want some tool like Java's StringBuffer that you can just call .append(byte b) or .append(byte[] buf) and ...
- 16.1k
72
votes
3
answers
67k
views
Binary buffer in Python
In Python you can use StringIO for a file-like buffer for character data. Memory-mapped file basically does similar thing for binary data, but it requires a file that is used as the basis. Does Python ...
- 5,872
67
votes
3
answers
157k
views
Buffer entire file in memory with Node.js
I have a relatively small file (some hundreds of kilobytes) that I want to be in memory for direct access for the entire execution of the code.
I don't know exactly the internals of Node.js, so I'm ...
- 2,992
64
votes
14
answers
30k
views
Should a buffer of bytes be signed or unsigned char buffer?
Should a buffer of bytes be signed char or unsigned char or simply a char buffer?
Any differences between C and C++?
Thanks.
- 17.5k
62
votes
6
answers
47k
views
When to use .NET BufferedStream class?
The MSDN site states:
A buffer is a block of bytes in memory
used to cache data, thereby reducing
the number of calls to the operating
system. Buffers improve read and write
performance. A ...
- 89.8k
60
votes
3
answers
28k
views
Is there a way to programmably flush the buffer in log4net
I'm using log4net with AdoNetAppender. It's seems that the AdoNetAppender has a Flush method. Is there anyway I can call that from my code?
I'm trying to create an admin page to view all the entries ...
- 4,062
60
votes
4
answers
63k
views
File I/O with streams - best memory buffer size
I am writing a small I/O library to assist with a larger (hobby) project. A part of this library performs various functions on a file, which is read / written via the FileStream object. On each ...
- 1,641
59
votes
5
answers
64k
views
Pipe buffer size is 4k or 64k?
I read in multiple places that the default buffer size for a pipe is 4kB (for instance, here), and my ulimit -a tends to confirm that statement:
$ ulimit -a
core file size (blocks, -c) 0
...
- 13.4k
58
votes
5
answers
32k
views
Why doesn't Ruby have a real StringBuffer or StringIO?
I recently read a nice post on using StringIO in Ruby. What the author doesn't mention, though, is that StringIO is just an "I." There's no "O." You can't do this, for example:
s = StringIO.new
s &...
- 64.9k
55
votes
6
answers
25k
views
How to redirect ex command output into current buffer or file?
How can I redirect or pipe the output of an ex command into my current buffer or a file?
For example, I want to read the contents of all the registers into the current buffer, which in ex mode is ...
- 11.2k
52
votes
3
answers
9k
views
How can I save my mini-buffer history in Emacs?
I'd like to save, for instance, my find-file and Meta-X history in Emacs' mini-buffer so I can recall commands later in a different session.
- 21.5k
50
votes
1
answer
68k
views
How to know actual size of byte buffer`s content in nodejs?
I get files as byte buffers and cannot use fs.stat() method.
So I am try to use buf.length but this length refers to the amount of memory allocated for the buffer object and not actually the content ...
- 704
50
votes
2
answers
28k
views
Use of Vertex Array Objects and Vertex Buffer Objects
I am trying to understand these two, how to use them and how they are related. Let's say I want to create a simple terrain and a textured cube. For both objects I have the array of triangles vertices ...
- 11k