Methods of storing application data/settings without the registry?

Question

I need some methods of storing and getting data from a file (in WIN32 api c++ application, not MFC or .NET)

eg saving the x, y, width and height of the window when you close it, and loading the data when you open the window.

I have tried .ini files, with the functions -- WritePrivateProfileString and ReadPrivateProfileString/Int, but on MSDN it says

"This function is provided only for compatibility with 16-bit Windows-based applications. Applications should store initialization information in the registry."

and when i tried on my Windows7 64bit machine to read a ini file, i got blue screen! (in debug mode with visual studio) OO

I notice that most other application use XML to store data, but I don't have a clue how to read/write xml data in c++, are there any libraries or windows functions which will allow me to use xml data?

Any other suggestions would be good too, thanks.

Answer 1

There is nothing wrong with .ini files, the only problem with them is where to write them. CIniFile from CodeProject is good enough class. Ini file should be placed in %APPDATA%/<Name Of Your Application> (or %LOCALAPPDATA%\\<Same Name Here> , as described below).

EDIT: If we are talking about Windows family of operating systems from Windows 2000 onward then function SHGetFolderPath is portable way to retrieve user specific folder where application configuration files should be stored. To store data in romaing folder use CSIDL_APPDATA with SHGetFolderPath . To store data to local folder use CSIDL_LOCAL_APPDATA.

The difference between local and roaming folder is in the nature of the data to be stored. If data is too large or machine specific then store it in local folder. Your data (coordinates and size of the window) are local in nature (on other machine you may have different resolution), so you should actually use CSIDL_LOCAL_APPDATA.

Windows Vista and later have extended function SHGetKnownFolderPath with its own set of constants, but if you seek compatibility stick to the former SHGetFolderPath .

Answer 2

TinyXML is a popular and simple XML parser for C++.

Apart from that, you can really use any format you want to store your settings, though it's considered good practice to keep settings in text format so that they can be hand-edited if necessary.

It's fairly simple to write your own functions for reading/writing a file in INI or similar format. The format is entirely up to you, as long as it's easily comprehensible to humans. Some possibilities are:

; Comment
# Comment
Key = Value (standard INI format)
Key Value
Key: Value

Answer 3

You could use Boost.PropertyTree for this.

Property trees are versatile data structures, but are particularly suited for holding configuration data. The tree provides its own, tree-specific interface, and each node is also an STL-compatible Sequence for its child nodes.

It supports serialization, and so is well-suited to managing and persisting changeable configuration data. There is an example here on how to load and save using the XML data format that this library supports.

The library uses RapidXML internally but hides the parsing and encoding details, which would save you some implementation time (XML libraries all have their idiosyncracies), while still allowing you to use XML as the data representation on disk.

Answer 4

Libconfig is the best solution in C++ as far as I have tried. Works multi platform with minimum coding. You must try that!

Answer 5

libxml2 . I have seen quite a lot places where it is used. Easy to use and loads of examples to get you started and not a vast library as such. And in C, take it wherever you want.

Answer 6

pugixml is another good (and well documented) XML parser library. And If you like portability XML is a better option.

Answer 7

While INI files may not be the best format, I think you can safely ignore the warning MSDN puts on WritePrivateProfileString and ReadPrivateProfileString.

Those two functions are NEVER going away. It would break THOUSANDS of applications.

That warning has been there for years and I suspect was added when the registry was all the rage and someone naively thought it would one day completely replace INI files.

I might be wrong but it would be very unlike Microsoft to break so many existing apps like this for no good reasons. (Not that they do not occasionally break backwards compatibility, but this would cause huge problems for zero benefit.)

Answer 8

Ohhh My GOD? Have you ever thought of stright-forward solution rather then thinking of Super-Duper-all-can-do framework way?

Sorry...

You want to store two numbers between restarts???

Save: Open a file, write these two numbers, close the file:

std::ifstream out(file_name);
out << x << ' ' << y;
out.close();

Load: Open a file, read these two numbers, close the file:

std::ifstream in(file_name);
if(!in) return error...
in >> x >> y;
if(!in) return error...
in.close();

Answer 9

Come on, just save the data you need in a text file. You can also write a thin wrapper API for that functionality. What's the problem?