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Using C/C++ code, How to read a text file (approx size 100GB) line by line from a remote machine in LAN directly without downloading or copying the file
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You would need a client application on the remote system, or remote access, to read the file and pass the data to your program.
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With a typical client/server application, your TCP server runs on the remote machine, waiting for 'gimme next line' command from the client. On command reception, it reads the line and answers to the client with the read line content.
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is the machine doing the reading on the same network as the machine with the file? If so, just use a UNC, something like:
\\machine\folder\...\file.ext
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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Nice. 
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I am working with embedded C and sometimes I compile with Eclipse/GCC and sometimes with STMicroelectronics System Workbench. In my code there are a lot of nested macros and I think it would be great to display the expanded macro value as a comment right after the macro (note: only the macros without parameters). So I was thinking of having a post-build .exe-file/script that takes the result from the precompiler and puts it back into the source code as comments after the macros. As an alternative, I could have a pre-build .exe-file/script that executes the pre-compiler (meaning it will be executed twice for each compile) and then modifies the source code. I feel fairly confident about writing the .exe-file/script, but I have no idea how to execute the precompiler "on demand" or how to view the results of it. Could someone please provide some guidelines on how to achieve this? I know pretty much nothing about makefiles, precompilers, compilers, etc, so please feel free to formulate your answers in this thread in the way you would communicate with a beginner programmer.
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See Overall Options (Using the GNU Compiler Collection (GCC))[^]. The -E option of gcc allows you to stop the build after running the preprocessor. The out put will be the expanded source. But be aware that this will include the expansions of all input from included headers so may well be quite extensive. If you run a few samples you should be able to see how to get to the source that you are interested in.
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I just tried it, but it seems I need to reference the macros in order to get the expanded values. Most of my macros are never referenced in the project I would like to generate the explanatory comments in, they are just defined in a (shared) .h-file.
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If they are not used then the preprocessor will ignore them. Macro expansion happens at the reference, not at the definition. You may need to create some dummy file to get the expansions. A better idea would be to write proper documentation comments so they can be seen by anyone looking at the definitions. And I think that may also make them visible through intellisense.
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I am creating an application using c# winform to create and mount ISO files like wincdemu. I am able to create the ISO file and mount it like a local drive. I want to mount the image with disc type CD-ROM/DVD-ROM. I am using AttachVirtualDisk() to mount the image.
Is there any API/library support to mount the image with disc type CD-ROM/CD-R/CD-RW/DVD-ROM/DVD-RAM etc. ?
I appreciate any advice.
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You might be better off asking in the C# forum.
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment
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Hello,
We use a third party library for our grids. Each grid cell has a style, one member of which is the font:
class CLibStyle
{
[...]
CLibFont m_pFont;
[...]
};
During deserialization serialization in the library methods, the font is managed as follows:
ar >> m_pFont;
For our part, we deserialize the styles line by line, column by column, then storing them in a map to use them later:
CLibStyle * pStyle = NULL;
for (int nNumRow = 0; nNumRow ++; nNumRow <nNbRow)
for (int nNumCol = 0; nNumCol ++; nNumCol <nNbCol)
{
pStyle = new CLibStyle();
pStyle->Serialize(ar);
mapStyle->AddTail(pStyle);
}
So far it's very basic but this is where we have a big problem because it happens that this deserialization, as simple as it is, allocates pointers m_pFont on the same memory areas from one loop to another. With the same archive file, this problem does not necessarily arise depending on whether you are in Debug or in Release, or even differs from one PC to another. 
Afterwards, we inevitably have problems even if the pointers are destroyed ...
Any ideas for ensuring that pointers are not allocated on the same memory range?
Thanks a lot for your help.
modified 25-May-20 3:49am.
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Hello,
I'm not sure to understand how the "serialization" works in your exemple.
What is ar ?
ar >> m_pFont
m_pFont is a pointer, so in my opinion, there is no allocation here, only a pointer (ar) affected to another pointer (m_pFont). You probably have one instance of your font ( managed by your code or the library, I don't know ) referenced ( pointed ) by several m_pFont.
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You appear to be confusing serialization and deserialization. The first line above ar >> m_pFont; is deserializing from the archive into the m_pFont object. So where is the deserialize code that loads the object from the archive, and what type is m_pFont?
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You are right. I've just modified and corrected my previous post ...
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Well, in fact, I've two cases :
if I serialize with the following way, I've got some CLibStyle::m_pFont on the same memory during the serialization :
CLibStyle Style;
for (int nNumRow = 0; nNumRow ++; nNumRow <nNbRow)
for (int nNumCol = 0; nNumCol ++; nNumCol <nNbCol)
{
Style.Free();
m_pGrid->GetStyleRowCol( nRow, nCol, Style);
Style.Serialize(ar);
}
if I serialize with this second way, I've got problem during deserialization in the ar >> m_pFont line : CArchive::ReadObject can't find the corresponding runtime class ...
CLibStyle *pStyle;
for (int nNumRow = 0; nNumRow ++; nNumRow <nNbRow)
for (int nNumCol = 0; nNumCol ++; nNumCol <nNbCol)
{
pStyle = new CLibStyle();
m_pGrid->GetStyleRowCol( nRow, nCol, *pStyle);
pStyle->Serialize(ar);
}
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Well your code remains unclear. However, if m_pFont is a pointer, then you are going to have problems unless you also serialize the object that it is pointing at. Deserializing a pointer without the underlying object means that it will be pointing to some random portion of memory.
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This point is treated by the MFC CArchive::ReadObject and CArchive::WriteObject methods which are automatically called by the >> or << operator. They are able to detecte or serialize the associated RuntimeClass.
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Well if that is working then you need to use your debugger to find out what is going wrong. Also it is still not clear exactly what is wrong when you have deserialized from the archive.
The comments at Storing and Loading CObjects via an Archive | Microsoft Docs[^] seem to imply that you may need to use the Serialize function rather than the insertion/extraction operators.
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The most obvious flaw I can see is that your are interverting loop test and variable increment in your for loops.
The syntax is
for (init; condition; increment) , and you are using
for (init; increment; condition) instead.
"Five fruits and vegetables a day? What a joke!
Personally, after the third watermelon, I'm full."
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Well spotted, but I would expect his app to crash if that is in the actual running system.
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Yes, very well spotted ... I wrote the sample code too quickly 
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