I am using a .mdb file as a database for a dialog based application. For the each Release I want to give a version to the mdb file if there are more entries added. using C++ i want to read the version and display it in the application.
Can you please tell me if it is possible to give a version to mdb file ?
You can add a table to MDB and track releases there. If MDB should change release number automatically after some data changes, you can use Data Macro (this is for Access 2010+)
You can create a custom property:
db.CreateProperty("VersionId", dbText, "1.0.0")
then add this to the database, but there is no way to read this without opening the database file.
There is no easy way to do that and its probably best to do it as a db.property like #Gustav proposed.
If for some reason it is important to have a version information that you can read without opening the file as access file there are still some options:
There is the Windows Shell Property System that I think allows you to add Properties to every File/Folder.
You could change the Creation Date for the file to fit your need.
You could perhaps even read/change the file content itself in a binary stream if you research it thouroughly enough.
and you can of course have an external .txt (or .ver or whatever) file that you update automatically from the db.property whenever you open the db.
Related
Can we add metadata to unlink/remove a file after x-time automatically. That is system automatically removes that file, if it finds that particular metadata attached with that file
Note- file can be present at any location, and user may move that file anywhere on their system, but based on that metadata file should get deleted(i.e system should call unlink/remove) for that file.
Is there a cocoa/objective-c/c++ api to set such metadata/attributes of a file?
The main point is i am creating an application through which i am providing some trial files to the user, and those files are also usable by other application which recognises them. After trial expiry, i want to delete those files, but user can always move my files to a different location and use them forever, how to protect those files from permanent use?
No, there is no built-in mechanism to auto-delete a file based on some metadata.
You could add the feature yourself, with an accompanying agent that would trawl for files with the metadata and delete them when the time came.
If you are doing this for good housekeeping you can follow #Petesh answer.
If you are doing this because you really want those files gone then no. The user could move the file to a USB stick and remove it, or edit the metadata, etc.
Your earlier question "Completely restricting all types of access to a folder" seems to addressing the same issue and the suggestions are the same as given there - use encryption or implement your own file system.
E.g. have a special "trial file" format which is the same as the ordinary format - which is readable by other apps - but encrypted and includes an expiry date. Your app then decrypts the file, checks the date, and either does its thing or reports to the user the file is out of date.
The system isn't unbreakable, but its a reasonable barrier - easy for you to do, too hard for the average user to break.
I have following scenario:
The main software I wrote uses a database created by a simulator. This database is around 10 GB big at the moment, so I want to keep only one copy of that data per system.
Assuming I have following projects:
Main Software using the data, located at /SimData
DLL using the data for debugging, searching for data at /SimData
Debugging tool to parse the image database, searching for the data at /SimData
Since I do not want to have all those programs have their own copy of SimData (not only to decrease place used, but also to ensure that all Simulation data used is always up to date for all programs).
I created for the DLL and Debugging Utility a link named SimData to MainSoftware/SimData, but when opening a file with "SimData\MyFile.data" it cannot find it, only the MainSoftware with the ACTUAL SimData folder can find it.
How can I use the MainSoftware/SimData folder without setting absolute paths?
This is on Windows 7 x64
I agree with Peter about adding the DB location as a configurable parameter. A common place to store that is in the registry.
however, If you want to create links that will be recognized by your software, try hardlinks. . fsutil should do the trick as described here.
You need a way to configure the database location. You could use an INI or other configuration file, or a registry setting, or a command-line input, or an environment variable. Or You could write your program to search a directory hierarchy... for example, if the various modules are usually siblings of each other in your directory tree, you could search for SimData/MyFile.data, ../SimData/MyFile.data, ../../MainSoftware/SimData/Myfile.data, and use the first one found.
Which answer is the "right one" depends on your situation.
I created application that store some data to XML file. The issues is with the path of the XML saving. Am using TinyXML to save the data in vc++.
When I deploy this application, it installs in "C:\Program files(x86)\applicationname " and when I run the application the XML file is saving in
"C:\Users\UserName\AppData\Local\VirtualStore\Program Files (x86)\ApplicationName ".
I have made this application to work on system startup. So when I restart this application,
the xml file is stored in different path "C:\Users\UserName\AppData\Local\VirtualStore\windows\sysWOW64"
I want my XML to be stored in the path where I installed or should be stored in appdata, application name
What should I do to store XML file in one places where application is installed?
doc.SaveFile( "test.xml" ); // xml saving code in tinyxml library
Firstly, this has nothing to do with C++, as the C++ code is probably working. Same with XML and tinyxml and even visual-c++.
It seems that windows redirects those write accesses to a user-specific "VirtualStore\Program Files", but I'll leave it to you to research the actual semantics of that. On startup, when there is no user, this path obviously differs, since the former user is not logged in.
Now, in order to get a fixed path, you can use the function GetModuleFileName() to find out the location of your executable and use that path to locate Smartmeter.xml. However, the problem you are facing now is that programs installed under "Program Files" don't magically gain write access rights to their install directory. This is to protect one user from messing with data of another user.
I think that what you are doing is writing a program that runs in the background, which would be called a "service" under MS Windows. What is still unclear is what you want to achieve with this file and also what you are planning to do overall, and these are things that decide the future steps. In any case, take a look at the possibilities that services provide, maybe there is something that fits your needs.
Apparently this supposed to be possible. For example opening and operating on a file with NOTEPAD, or HxD. But aren't they all text files...how would one specify which text editor to open the file and operate on the file with using the WINDOWS API. It is certainly not in "CreateFile".
Hopefully I'm understanding your question... The easiest way to do this is to launch the desired editor and pass the filename as an argument, rather than "invoking" the file (which will launch the default program associated with the file type).
For example, notepad.exe mytextfile.txt or gvim.exe mytextfile.txt.
If the editor is not on your %PATH%, you'll need to use a full path file name.
What are you trying to do, exactly? You could:
Maintain a list of editors that you expect to be installed and have entries for in the system's PATH (bad idea)
Have an editor/editors that you want to use, query the Windows registry to find the installation path of the editors (using RegGetValue), and launch the editor with CreateProcess) (a little better idea)
Query the registry to get the default editor for a given file type and then launch that editor using CreateProcess. (best idea)
But it all depends on what your goal is really.
Edit based on requirements
So, just so we're on the same page, from C++, you want to:
Take a command line parameter to your C++ application (filename)
Open that file in an arbitrary editor
Detect when the user has made changes to that file
Operate on the file contents
Is that correct?
If so, you could:
Use Boost libs to compute a CRC for the current data in the file
Launch an editor using one of the methods I initially described
Stick in a tight loop and sleep so you don't chew up resources while the initially computed CRC matches one calculated every iteration of the loop
Of course, there are all kinds of issues that you'd have to deal with (that's just a super simple way of describing the algorithm I might use), such as:
What happens if the user doesn't change the file?
What happens if the file isn't found?
I'm sure that there are a number of different methods of doing this, but this is the easiest method that I can think of at the moment (while still being able to be fairly certain of the changes).
Disclaimer: I haven't implemented something like this, so I might be completely off base ;)
Are you looking for the ShellExecute() or ShellExecuteEx() APIs on Windows? They'll launch whatever program is registered for a file (generally based on the filename extention).
I wish to store a single variable in my application that will be saved between runs. This will be a version number that will be used to trigger an update option and so will change only rarely.
Does anyone have suggestions on the best way of implementing this? Considering it's such a simple requirement I am interested in the simplest solution.
Thanks!
Normally, that sort of information will be held in a constant (not a variable) in the binary, and the binary will contact an external site to find out whether there is a more recent version of the software. When it downloads the new, the newly downloaded file will have a new constant embedded in it.
Alternatively, you could keep the information in some sort of file in the file system. I'm not familiar with the Symbian environment, but something similar most likely exists.
It has already been mentioned, so I am going to elaborate on it. Create a file in your project directory that will contain the version number. Make that file a part of final SIS file by adding a line about it in the PKG file---for example, put a line in the PKG file to tell the installer to copy the file to a place like c:\System\Apps\${AppName}\${filename} on the device. Within code, read the version number from that file. The advantage you will have from doing it this way is that when you update your code and edit the file in your project directory and recreate an updated SIS file, on updating the SIS on the device, the version file will automatically get replaced with the current one.