The title is pretty self-explanatory: does anyone know of a (good) properties file reader library for C or, if not, C++?
[Edit: To be specific, I want a library which handles the .properties file format used in Java: http://en.wikipedia.org/wiki/.properties]
I guess by 'properties file' you mean config file.
In this case Google gives (first 4 hits for C config file library):
STLSoft's 1.10 alpha contains a platformstl::properties_file class. It can be used to read from a file:
using platformstl::properties_file;
properties_file properties("stuff.properties");
properties_file::value_type value = properties["name"];
or from memory:
properties_file properties(
"name0=value1\n name1 value1 \n name\\ 2 : value\\ 2 ",
properties_file::contents);
properties_file::value_type value0 = properties["name0"];
properties_file::value_type value1 = properties["name1"];
properties_file::value_type value2 = properties["name 2"];
Looks like the latest 1.10 release has a bunch of comprehensive unit-tests, and that they've upgraded the class to handle all the rules and examples given in the Java documentation.
The only apparent rub is that the value_type is an instance of stlsoft::basic_string_view (described in this Dr Dobb's article), which is somewhat similar to std::string, but doesn't actually own its memory. Presumably they do this to avoid unneccessary allocations, presumably for performance reasons, which is something the STLSoft design holds dear. But it means that you can't just write
std::string value0 = properties["name0"];
You can, however, do this:
std::string value0 = properties["name0"].c_str();
and this:
std::cout << properties["name0"];
I'm not sure I agree with this design decision, since how likely is it that reading properties - from file or from memory - is going to need the absolute last cycle. I think they should change it to use std::string by default, and then use the "string view" if explicitly required.
Other than that, the properties_file class looks like it does the trick.
libconfuse (C library) is useful, too; it's been around forever & is flexible.
It goes way, way beyond java.util.Properties. Though, it won't necessarily handle the corner cases of the java properties file format (which seems to be your requirement).
See the examples:
No C++ wrapper library, that I'm aware of, though.
I think the properties_file solution from stlsoft is no longer valid. Also the library lacks documentation and samples for properties_file, it seems promising but it is incomplete. I cant send message the post owner to update his post.
Also correct to code
using platformstl::properties_file;
properties_file properties("stuff.properties");
properties_file::view_type value = properties["name"];