Getting specfic files in C++ code from *nix system - c++

I want to get all the files of type A*.txt present in current directory via C++ code. My OS is *Nix system. Also, I want to get the names of such files.
Please suggest how can this be done.
I tried using system command but system doesn't return anything apart a integer which says if command was executed properly or not.
Thanks

There are basically three ways you can go about this.
One is to use basically what you tried before, but using the popen function, which allows you to read the output of the command(s) you run.
The second solution is to use e.g. opendir and readdir or scandir to manually filter and find the files you look for.
The third and easiest way is to use the glob function.
There is actually a fourth way as well, one which is platform independent and more C++-ish than the above methods: Using the Boost filesystem library.

Related

C++, console Application, reading files from directory

I have a directory and I want to read all the text files in it using C++ and having windows OS also using console application
I don't know the files' names or their number
thanks in advance
Take a look at Boost.Filesystem, especially the basic_directory_iterator.
If you want the C++ and portable way, follow the solution by #Space_C0wb0y and use boost.Filesystem, otherwise, if you want to get your hands dirty with the Windows APIs, you can use the FindFirstFile/FindNextFile/FindClose functions.
You can find here an example related to them.

Using windows CopyFile function to copy all files with certain name format

Hello! I am updating some C code that copys files with a certain name. basically, I have a directory with a bunch of files named like so:
AAAAA.1.XYZ
AAAAA.2.ZYX
AAAAA.3.YZX
BBBBB.1.XYZ
BBBBB.2.ZYX
Now, In the old code, they just used a call to ShellExecute and used xcopy.exe. to get all the files starting with AAAAA, they just gave xcopy the name of the file as AAAAA.* and it knew to copy all of the files starting with AAAAA. now, im trying to get it to copy with out having to use the command line, and I am running into trouble. I was hoping CopyFile would be smart enough to handle AAAAA.* as the file to be copied, but it doesnt at all do what xcopy did. So, any Ideas on how to do this without the external call to xcopy.exe?
Check this out as a starting point
http://msdn.microsoft.com/en-us/library/aa364418(VS.85).aspx
or even better this full example
http://msdn.microsoft.com/en-us/library/aa365200(v=VS.85).aspx
You could also use SHFileOperation or IFileOperation (the latter being only available from Vista upwards but is now the recommended way according to MSDN). SHFileOperation supports wildcards and displays a progress by default, but there's also a flag for silent operation.
Check out the following MSDN links for more info:
http://msdn.microsoft.com/en-us/library/bb762164(v=VS.85).aspx
http://msdn.microsoft.com/en-us/library/bb775771(v=VS.85).aspx
You would basically have to write code to reproduce the functionality in xcopy. To do so, you must build a list of files by accessing the path and recursing through it. Test each found entry with your pattern and keep only those that match. Then iterate over that list with CopyFile.
See the following set of functions that can help you build the file list:
http://en.wikipedia.org/wiki/Dirent.h
It might just be easier to keep using xcopy unless you have a specific reason not to.
There are lots of ways to do it. I'd probably use a loop of FindFirstFile() / FindNextFile().
However, is there any reason you can't still use xcopy? You can launch it with CreateProcess(). It isn't pretty, but it works.

Check file name is valid windows name

I wanna check if my string is valid windows file path. I was searching around and it seems that there is no reliable method to do that. Also I checked boost filesystem library , and no obvious function exist to do this check , maybe something like is_valid_windows_name
You could use _splitpath() function and parse the output (based on it, you could easily say if your path is valid or not).
See MSDN for additional information.
Note that this function is windows-specific.
I do not believe there is a standard c++ api for that.
Note that the Windows API allows more filenames than the Windows Shell (The filenames the user is allowed to use in windws explorer).
You should have a look at the windows shell api.
Another possibility is to use trial and error, this way you are truly independend of the current filesystem.
The easiest way is to disallow
\ / < > | " : ? *
and you should be fine.
Yes, there is a boost function that does what you want. Take a look at boost::filesystem::windows_name(...). You will need to include boost/filesystem/path.hpp as well as link against the correct (version- and architecture-specific) libboost_system and libboost_filesystem libraries since path is not a header-only lib.
It's a pity even the newest C++17 filesystem library doesn't have a function to verify file names.
You can use the Windows-specific Shell Lightweight Utility function PathFileExists or the Windows API GetFileAttributes and check the last error code specifically for ERROR_INVALID_NAME.
I think it's kind of a misuse (because there really should be a dedicated function for it) but serves the purpose.

Is there any standard way to load parameters from a file in C++ on Linux?

Imaging that a program needs to know quite a lot of parameters to do its tasks properly, such as 'Port = 2323' this kind of things.
now I want to save these parameters in a plain text file, similar to Unix' system variables such as users and groups.
Is there any standard way/libraries that can help me to do this? Does anyone ever used them before? thanks
Boost.Program_options library. Is this you are looking for?
The program_options library allows program developers to obtain program options, that is (name, value) pairs from the user, via conventional methods such as command line and config file.
Qt offers this by default, and in a cross-platform way. Checkout out QSettings
You can also create an alias or shell script that executes your program with given parameters. To conviniently get these parameters there's "getopt"
Link here for a cross platform ini handler.
Hope this helps.

C++ Passing Options To Executable

How do you pass options to an executable? Is there an easier way than making the options boolean arguments?
EDIT: The last two answers have suggested using arguments. I know I can code a workable solution like that, but I'd rather have them be options.
EDIT2: Per requests for clarification, I'll use this simple example:
It's fairly easy to handle arguments because they automatically get parsed into an array.
./printfile file.txt 1000
If I want to know what the name of the file the user wants to print, I access it via argv[1].
Now about how this situation:
./printfile file.txt 1000 --nolinebreaks
The user wants to print the file with no line breaks. This is not required for the program to be able to run (as the filename and number of lines to print are), but the user has the option of using if if s/he would like. Now I could do this using:
./printfile file.txt 1000 true
The usage prompt would inform the user that the third argument is used to determine whether to print the file with line breaks or not. However, this seems rather clumsy.
Command-line arguments is the way to go. You may want to consider using Boost.ProgramOptions to simplify this task.
You seem to think that there is some fundamental difference between "options" that start with "--" and "arguments" that don't. The only difference is in how you parse them.
It might be worth your time to look at GNU's getopt()/getopt_long() option parser. It supports passing arguments with options such as --number-of-line-breaks 47.
I use two methods for passing information:
1/ The use of command line arguments, which are made easier to handle with specific libraries such as getargs.
2/ As environment variables, using getenv.
Pax has the right idea here.
If you need more thorough two-way communication, open the process with pipes and send stuff to stdin/listen on stdout.
You can also use Window's PostMessage() function. This is very handy if the executable you want to send the options to is already running. I can post some example code if you are interested in this technique.
The question isn't blazingly clear as to the context and just what you are trying to do - you mean running an executable from within a C++ program? There are several standard C library functions with names like execl(), execv(), execve(), ... that take the options as strings or pointer to an array of strings. There's also system() which takes a string containing whatever you'd be typing at a bash prompt, options and all.
I like the popt library. It is C, but works fine from C++ as well.
It doesn't appear to be cross-platform though. I found that out when I had to hack out my own API-compatible version of it for a Windows port of some Linux software.
You can put options in a .ini file and use the GetPrivateProfileXXX API's to create a class that can read the type of program options you're looking for from the .ini.
You can also create an interactive shell for your app to change certain settings real-time.
EDIT:
From your edits, can't you just parse each option looking for special keywords associated with that option that are "optional"?