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i need to read numbers from a Textfile and store them in a linked list
so how do i read in from a file ?
please
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You can use CStdioFile
Nish
Sonork ID 100.9786 voidmain
www.busterboy.org
If you don't find me on CP, I'll be at Bob's HungOut
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Not a personal comment, but why do people always recommend MFC classes to do things that can be done using standard components ? I think it's better to learn stuff that is there no matter what you're doing in C++ ( and I mean ATL/MFC.Win32 more so than differing platforms ).
Christian
I have come to clean zee pooollll. - Michael Martin Dec 30, 2001
Picture the daffodil. And while you do that, I'll be over here going through your stuff.
Picture a world without war, without hate. And I can picture us attacking that world, because they would never expect it.
Sonork ID 100.10002:MeanManOzI live in Bob's HungOut now
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CG
My thinking is that when someone asks a question on how to read a text file, he must be looking for the easiest solution, otherwise he would not ask a question about reading a text file, which would be something covered in every C++ book ever written. And the MFC classes are the easiest way to read a file unless you want to use VB or Delphi.
Nish
Sonork ID 100.9786 voidmain
www.busterboy.org
If you don't find me on CP, I'll be at Bob's HungOut
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Nish [BusterBoy] wrote:
otherwise he would not ask a question about reading a text file, which would be something covered in every C++ book ever written.
This does not follow - how many 'in every book and easy to find in MSDN' questions do we answer here ?
Personally I find the IOStreams method I posted as easy and elegant as it gets, but I'm a one eyed fan of anything that's standard.
![Rose | [Rose]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/rose.gif)
Christian
I have come to clean zee pooollll. - Michael Martin Dec 30, 2001
Picture the daffodil. And while you do that, I'll be over here going through your stuff.
Picture a world without war, without hate. And I can picture us attacking that world, because they would never expect it.
Sonork ID 100.10002:MeanManOzI live in Bob's HungOut now
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Christian Graus wrote:
Personally I find the IOStreams method I posted as easy and elegant as it gets, but I'm a one eyed fan of anything that's standard.
To be honest, all that STL scared me. I couldnt make head or tail of the code you posted to the poor fella who only wanted to open a text file and read in a few numbers.
Am the only one here who does not understand or use STL?
Nish
Sonork ID 100.9786 voidmain
www.busterboy.org
If you don't find me on CP, I'll be at Bob's HungOut
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Nish [BusterBoy] wrote:
To be honest, all that STL scared me
I admit I felt the same when I started using it. But then, I felt that way about MFC as well....
Nish [BusterBoy] wrote:
Am the only one here who does not understand or use STL?
Sadly, I'd say you're in the majority. STL is SO much nicer than MFC container classes, but people are put off by the unfamiliar syntax and seem just to avoid learning it.
Christian
I have come to clean zee pooollll. - Michael Martin Dec 30, 2001
Picture the daffodil. And while you do that, I'll be over here going through your stuff.
Picture a world without war, without hate. And I can picture us attacking that world, because they would never expect it.
Sonork ID 100.10002:MeanManOzI live in Bob's HungOut now
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Let me walk you through how easy it is:
string currentLine;
The above line is irrelevant, it's left over from a line by line method I played with.
ifstream str("c:\\winzip.log");
if (!str.is_open())
{
cout << "It's stuffed\n";
return -1;
}
The above just opens a file and checks if it's OK.
vector<string> file_contents;
This defines a vector ( an array ) of strings.
copy(istream_iterator<string>(str),istream_iterator<string>(), back_inserter(file_contents));
This is the magic - the first argument means to iterate through the file a string at a time ( i.e. it does not expect only numbers, but any valid characters ), the second tells it to keep looking until the end of the file ( the return of the default constructor is the eof, back_inserter tells it to add the result to the end of the container specified, and the container to be copied into is our array.
// Now print out the results
copy(file_contents.begin(), file_contents.end(), ostream_iterator<string>(cout, "\n"));
This simply copies the entire array to the ouput stream. Pretty sweet, don't you think ? How else could you print an entire array, or read an entire file into an array, with one line of code ?
It's the algorithms that plug into the STL containers that make it light years ahead of MFC containers.
Christian
I have come to clean zee pooollll. - Michael Martin Dec 30, 2001
Picture the daffodil. And while you do that, I'll be over here going through your stuff.
Picture a world without war, without hate. And I can picture us attacking that world, because they would never expect it.
<Center><A href = "http://www.sonork.com" target = "_Blank">Sonork</A> ID 100.10002:MeanManOz</Center><Center>I live in <U><B>Bob's HungOut</B></U> now</center>
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Now that you have explained it, it sounds good.
I mean you can do so much with so little code.
Hmmmm. Maybe if I ever survive my COM learning attempts I might try out some simple STL too 
Thanks CG
Nish
Sonork ID 100.9786 voidmain
www.busterboy.org
If you don't find me on CP, I'll be at Bob's HungOut
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Nish [BusterBoy] wrote:
I might try out some simple STL too
Join us... don't be afraid....
Seriously, it's not hard once you get into it, I spent a lot more time trying to fathom out COM than I did STL. And obviously I'll be here to help if you get stuck..
Christian
I have come to clean zee pooollll. - Michael Martin Dec 30, 2001
Picture the daffodil. And while you do that, I'll be over here going through your stuff.
Picture a world without war, without hate. And I can picture us attacking that world, because they would never expect it.
Sonork ID 100.10002:MeanManOzI live in Bob's HungOut now
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Christian Graus wrote:
Join us... don't be afraid....
LOL
That sounds like right out of a thriller movie.
You are a revolutionary leader. I am the cool hero confused as to whether I should continue being a handsome playboy screwing french women or whether I should join the revolution. Finally I give in and we take over the solar system. You are made king and I become a count [you give me one of the jovian moons] and marry a beautiful princess born and brought up in Mars and live happily ever after
Nish
Sonork ID 100.9786 voidmain
www.busterboy.org
If you don't find me on CP, I'll be at Bob's HungOut
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Nish [BusterBoy] wrote:
Christian Graus wrote:
Join us... don't be afraid....
LOL
That sounds like right out of a thriller movie.
Actually I'm quoting Dilbert, the pointy haired boss to be exact. But yours sounds like more fun....
Christian
I have come to clean zee pooollll. - Michael Martin Dec 30, 2001
Picture the daffodil. And while you do that, I'll be over here going through your stuff.
Picture a world without war, without hate. And I can picture us attacking that world, because they would never expect it.
Sonork ID 100.10002:MeanManOzI live in Bob's HungOut now
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First of all, please only ask the one question once.
Secondly, the following code should work, assuming the numbers are properly delimited. It currently reads in strings, but you can use atoi, or convert it to read int's, I am sure.
This program is my playground for using IOStreams, so I sure there are #include and using std:: statements in there that are not needed.
<pre>
#include "stdafx.h"
#include <string>
#include <vector>
#include <algorithm>
#include <fstream>
#include <iostream>
#include <sstream>
using std::copy;
using std::vector;
using std::string;
using std::ifstream;
using std::ostream_iterator;
using std::cout;
using std::back_inserter;
using std::getline;
using std::ostringstream;
using std::istream_iterator;
int main(int argc, char* argv[])
{
string currentLine;
ifstream str("c:\\winzip.log");
if (!str.is_open())
{
cout << "It's stuffed\n";
return -1;
}
vector<string> file_contents;
copy(istream_iterator<string>(str),istream_iterator<string>(), back_inserter(file_contents));
// Now print out the results
copy(file_contents.begin(), file_contents.end(), ostream_iterator<string>(cout, "\n"));
return 0;
}
</pre>
Christian
I have come to clean zee pooollll. - Michael Martin Dec 30, 2001
Picture the daffodil. And while you do that, I'll be over here going through your stuff.
Picture a world without war, without hate. And I can picture us attacking that world, because they would never expect it.
<Center><A href = "http://www.sonork.com" target = "_Blank">Sonork</A> ID 100.10002:MeanManOz</Center><Center>I live in <U><B>Bob's HungOut</B></U> now</center>
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Nice. By the simplicity of the original post (he didn't ask how to find 4000-digit primes in constant time), I would have guessed they were asking for the simple fopen(), fgets(), etc.
But this is a nice solution. Prolly waaaaay over the poster's head.
J
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Jamie Hale wrote:
I would have guessed they were asking for the simple fopen(), fgets(), etc.
I had a look at those functions last night ( fulfilling a contract at the last minute, he wanted me to use them ), and I thought they looked way ugly. I try to avoid C functions whenever I can.
Jamie Hale wrote:
But this is a nice solution. Prolly waaaaay over the poster's head.
Probably. My hope was by showing an elegant C++ way of doing it that he may well dig deeper and analyse why it all works. That's how I learned most of the standard C++ stuff I know, by asking questions on comp.lang.c++, making a fool of myself often, and spending a lot of time trying to figure out what the answers I was given meant.
Christian
I have come to clean zee pooollll. - Michael Martin Dec 30, 2001
Picture the daffodil. And while you do that, I'll be over here going through your stuff.
Picture a world without war, without hate. And I can picture us attacking that world, because they would never expect it.
Sonork ID 100.10002:MeanManOzI live in Bob's HungOut now
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Hi,
Does anyone know how to install a callback function between two applications?
I guess that this shouldn't be too difficult (basically you just have to transmit a callback address), but I'm worring about the operating system shifting my applications in the memory. In this case the address isn't correct anymore, is that right? Is there an easy way of doing this?
Thanks for your help
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You do not need to worry about the OS moving your application around in memory because you only deal with a virtual address, and that will not change, however, the virtual address that you receive in process A will not be valid in process B. This makes calling a callback function not as simple as you would think.
You will need to do some form of inter-process Communication (IPC).
There are a number of ways that you can do this including, I listed these in an order of difficulty from easiest to most difficult:
Send a message to the second process and the message handler will call the function for you.
Create a COM object.
Use a memory mapped file to communicate between the two applications, monitor the data that is written in to the file and take appropriate actions.
Use a Remote Procedure Call (RPC). This is a networking mechanism that will scale to applications located on other machines, probably overkill in your case.
I would suggest the message mechanism. This is the same mechanism that you would probably use in a multi-threaded application.
Kilowatt
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Thanks for your answer
Just another question: if I solve the problem by using messages between the two processes, this means I use messages to tell the second application the address of the callback? Or use the messages instead of the callback?
My concret problem: I have an application which renders a 3D world. The 3D world is refreshed continuously everytime the message queue is empty.
I have a second application which can make modification to some objects in the 3D world through a dll with a shared data segment. The modifications are not directly reported on the 3D world, because all modifications have to be done just before the rendering. The modifications are stored in the shared data segment until a "redraw"-command is executed. I think everything would be easier if I could install a callback (in which I can update the data) which is called just before the rendering.
Can't I somehow deduce the absolute adress of a callback function given the virtual adress?
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The reason why you cannot do this is because you cannot access the memory in the second process. If you call the callback function in process 1 with an address of a function that you determined from process 2, you will be accessing the data this is at the memory location in process 1. This will most likely result in a memory access error.
WIN32 allows each application to have their own completely independent address space. This is why you cannot match the memory from one process to another. Even if you could find the absolute or physical address of the function call to the redraw command in your second app, the OS would change this address out from under you. That is why it is nice to work with virtual memory addresses, the memory moving becomes transparent to the application programmer. This would not be an issue in WIN16 because all applications shared the same address space.
The reason why you can access the shared data segment of the DLL and modify the memory is because windows maps the shared data segment of the DLL into a memory mapped file.
Since you already have shared data, you may just want to set an update bit that the Rendering app can monitor in its idle state and determine if it is time to update.
kilowatt
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alright;
now i need to read a sequence of numbers from a file and then store them in a linked list.
thanks
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Hi.
I am experience recursive random number. It seems that only happens when rand() is in a loop.
For example:
--------------------------------------
srand(time(0));
int tempNUM = 0;
for (int i = 0; i < 1000; ++i)
{
tempNUM = 1 + rand() %9999999;
cout << tempNUM + 1;
}
--------------------------------------
In a program I am working on with a similar code to the one above, the program generates duplicates random numbers. It seems I have to *wait* one second clock until it generates a something new. Does that have something to do with time(0)?
I would like something that can generate a completely random number almost instantaneously even when it is in a for loop like the one above.
Thanks,
Kuphryn
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If you read the time() docs, you'll see the return value is a time_t, which counts seconds.
--Mike--
"COM didn't solve the old version of DLL hell - it just provided us with a new and improved version of hell."
-- John Simmons, 1/22/2002
My really out-of-date homepage
Sonork - 100.10414 AcidHelm
Big fan of Alyson Hannigan.
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Make sure that srand() is called exactly once in your program. Your sample code works correctly because srand() is called outside of the loop.
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Thanks.
You are right. I did not call srand() inside the for-loop, but I did call it at the beginning of a function that I think could be recursive. I was prepare for school lastnight and was not able to look up all the code. I am certain srand() is the problem. You are right on.
Kuphryn
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I figured probably that most Win32 API gurus hang out here, and anyway, I posted a question in the VB forum (since the app i am talking about is written in VB) and as much as I hate to cross-post, I think it is an API problem, so allow me to post a link.
Please help if you can. Would be much appreciated 
The thread
--
David Wengier
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