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Hi, how to use iterators in file stream can any one explain me with sample code, that read and write files using iterator
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Please explain what you are trying to achieve. Files and iterators are two completely different concepts.
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Really? I was under the impression that istream_iterator and ostream_iterator were for exactly that purpose.
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Looking at the other replies, I realized that I misunderstood his question. I thought that he wanted to serialize a container and use the iterators to save the data. that's why I asked him more information.
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something like that (snatch from a google search):
std::ifstream ifs("filename.txt");
std::string str((std::istreambuf_iterator<char>(ifs)), std::istreambuf_iterator<char>());
?
Watched code never compiles.
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Maximilien wrote: std::ifstream ifs("filename.txt");std::string str((std::istreambuf_iterator<char>(ifs)), std::istreambuf_iterator<char>());
Something like this is much faster,
std::ifstream stream("c:\\test.txt");
if (stream.good())
{
std::stringbuf buf;
stream>>&buf;
std::string str(buf.str());
stream.close();
}
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At the risk of sounding glib, you can use stream iterators with any stream, whether they're from memory, sockets, files.
So if I have a lump of integers in a vector:
int init_data[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
std::vector<int> data( &int_data[0], &int_data[10] );
I can pump them out to any stream using the copy algorithm. So:
std::copy( data.begin(), data.end(), std::ostream_iterator<int>( std::cout, "\n" ) );
will write that lot out to std::cout separated by newlines. If you replace std::cout with the name of an ofstream then those values will tbe written to the file instead. Replace it with the name of an ostringstream and the data will end up in a string.
To read from a stream is much the same, except you use an istream_iterator:
std::vector<int> data;
std::copy( std::istream_iterator<int>( std::cin ), std::istream_iterator<int>(), std::back_inserter( data ) );
will read integers from standard in until something goes wrong with the stream (end of file, I/O error, run out of memory) and dump them at the back of data.
And of course it's not just copy - you can use any std algorithm that can handle input/output iterators. So as two examples you can transform a file into another one or accumulate the values in another. Basically any single pass operation you can do on a list or vector you can do on a file or pair of files in the same manner.
Cheers,
Ash
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If you want to learn about iterators, I can recommend that you implement a few. It's a great way of learning what it is, the difference between the various types, forward/random access/bidirectional/etc, and in what situations an iterator is a good or bad choice. It's also a great lesson in efficiency as well as a way of getting to know stl in general a bit better.
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Hey there guys,
Okay I have my current code working for GLFW. Effectively i'm just trying to build a small main-frame which I can build on. I have IniApi.cc that stores the main() routine. I have CharKeyCallback.cc which handles the glfwSetCharCallback() just fine.
However, i'm trying to make a Texture class which will load textures from a file and store them in memory. So, I placed this at the top of the Texture.cc file:
#include <Windows.h>
#include <GL/glfw.h>
#include <stdio.h>
#include "Texture.h"
And my "load" function works like this:
bool Texture::ReadImage()
{
glfwReadImage(_filename, ImageData, _flags);
return !(ImageData == NULL);
}
(If it appears messy or simple, it's because i'm just laying the foundations at the moment).
However, when I go to compile, I receive the following error:
error LNK2019: unresolved external symbol _glfwReadImage referenced in function "public: bool __thiscall Texture::ReadImage(void)" (?ReadImage@Texture@@QAE_NXZ)
Now, my InitApi.cc runs the lpfw functions just fine, which means the library & DLL have been loaded (glfwOpenWindow opens a window successfully) but Texture.cc won't recognise the lpfw functions, even though i've included #include <GL/glfw.h> at the top.
Any suggestions? Thank you 
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Nevermind.
For those who might encounter this problem, it turns out I had to add #define GLFW_DLL before the #include <GL/glfw.h>
Resolved.
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Is there any function in C++ or C that checks if there is a character in the standard input and returns immediately? I have this application that creates a new thread when it starts working on an assigned task. The new thread asks the user to press some keys for other options as the main thread does its work. What I want is that if the main thread finishes doing its work and the user has not selected any of the options, then the thread that was created to get user options should return. But because the new thread waits for user input, I'm finding it difficult to stop it from waiting for user input so that it can return. I initially thought cin.peek() could do it but it also waits when the user has not press any key. I want a way to terminate the new thread as it waits for input, when the main thread has finished its work. Please help.
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_kbhit [^].
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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use _getch(), the header file is conio.h
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_getch() actually waits for the user input.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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How to Hide the TilteBar of a window Created Using CMFCToolBar in Floating Style
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You can try calling ModifyStyle(WS_CAPTION, 0), but if you remove its title bar you loose the ability to meve it (and then you cannot dock it again by dragging its window near the main window border)...
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Hi,
My application is MDI application.
In that im having one SDI view(CGlgPopup) derived it from CFrameWnd.
Now for that view,i want to remove Maximize,minimize button and also i want to set the size of the view as small like 200x200 size.
In PreCreateWindow() of CGlgPopup class,
i did like
cs.style &= ~(WS_MAXIMIZEBOX);
cs.style &= ~(WS_MINIMIZEBOX);
cs.style &= ~(WS_CHILDWINDOW);
cs.x = xPosVal-60;
cs.y = yPosVal-50;
cs.cx = 400;
cs.cy = 300;
But the expecting result is not coming.
How can i do that?
Anu
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Hi all,
I am trying to trim a string and store the values in some variable.
i.e
I have
CString str = sample(1,2,3,4,5);
I want to store the values as
x1=1,x2=2,x3=3......so on.
Any idea how can i proceed will be thankful
Thanks in advance
Raj
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I assume you mean
CString str = sample("1,2,3,4,5");
You can use std::stringstream, ::strtok(), CString::Find(), or maybe boost::split(). Try each of them and see how they differ.
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Dear, Firstly assign object of CString correctly.
modified on Wednesday, August 25, 2010 2:44 AM
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What's wrong with assigning a variable from a function call?
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No problem, that's
CString sample(int a, int b, int c, int d, int e)
{
CString str;
str.Format("%d,%d,%d,%d,%d", a,b,c,d,e);
return str;
}
CString str = sample(1,2,3,4,5);
just pure humour!
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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raju_shiva wrote: CString str = sample(1,2,3,4,5);
The above instruction is not correct.
Supposing it is:
CString str = "sample(1,2,3,4,5)"
I would use CStringT::Tokenize [^], have a look at the sample code provided.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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CPallini wrote: Supposing it is:
CString str = "sample(1,2,3,4,5)"
Actually i am reading it from edit box as a CString.
i.e
CString str = "sample(1,2,3,4,5)"
I am trying with this code
CString str = "sample(1,2,3,4,5)",str1,str2;
str1 = str .Left(str .Find("("));
str2 = str .Right(str .Find("("));
str.Left is working fine
I am getting the result as sample
But str.Right i am not getting the required result as 1,2,3,4,5).
I am getting 3,4,5
What i am doing wrong
Thanks
Raj
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