Is there a good, simple library which allows C++ to load a webpage? I just want to grab the source as text. I'm not using any IDE or significant library, just straight command line.
Tangentially, is there something fundamental I'm missing about programming in C++? I would think any language in common use today would have droves of web-based functionality, being so central to computer usage, but I can find next to no discussion on how to accomplish it. I realise C++ significantly predates the modern internet, so it lacking any core ability in the regard is reasonable, but the fact that relevant libraries seem so sparse is baffling.
Thanks for your help.
Sure, for example libcurl is powerful and popular.
Internet-related libraries for C++ are extremely abundant -- they're just not part of the C++ standard, partly because the current version of that standard is so old, though I'm sure that's not the only reason. But turn to the world of open sources and you'll find more than you can shake a stick at.
libcurl is a popular C library for fetching HTTP and other URLs. There's also cURLpp a C++ binding .
On Windows you have the WinINet and WinHTTP APIs.
I think HTTP is a bit too complex to be part of the C++ Standard Library. The specification would have to take a lot of details into account such as proxy servers and MIME types.
Related
What is the most basic way to go to a webpage and download its contents? the webpage i wish to get only has text, most of which is in tables.
is there a std library that does it (like urllib in python)?
There's no official C++ network library, no. There are many different APIs available, though. Which is best for you would depend on what platform(s) you were targeting and what framework(s) you might already be using.
That said, cpp-netlib is a platform-neutral API that follows C++ idioms nicely. I've used it and it works.
A large number of tasks that are not covered by the C++ standard library can be done using boost, the collection of peer-reviewed portable libraries, which are used by pretty much every C++ project today. For networking, we use boost.asio.
Their tutorials include HTTP clients: http://www.boost.org/doc/libs/1_46_1/doc/html/boost_asio/example/http/client/sync_client.cpp and http://www.boost.org/doc/libs/1_46_1/doc/html/boost_asio/example/http/client/async_client.cpp
However, although this is highly portable and may end up becoming part of the C++ standard library in future, it is a bit too low-level for your task. libCURL is the today's default library for HTTP downloads.
I am a student, and new to C++. I am searching for a standard C++ API that is as comprehensive as the Java API. So far I have been using cplusplus.com, and cppreference.com.
Please any help would be greatly appreciated.
C++ and Java have very different standard libraries because they make very different assumptions about what they are going to be used for.
Java assumes that applications or applets will be running on a host with a full featured OS, with a defined way of doing most normal things.
There's a lot of content in that, for instance, in java, the output will be an application or applet. C++ does not make that assumption, because C++ can be used for building OS Kernels and drivers for kernels, it can be used for programming full stack real time applications on microcontrollers, or processing blocks in supercomputers.
C++ can be used for implementing the very operating system on which it will run.
For these reasons, the standard library assumes almost nothing about what it will have available, and so the standard library doesn't make any dependencies on those features.
The only exception is with files and streaming, because almost any operating system like stack has something that looks like a file stream if it has anything like files at all.
If you want a richer set of OS Specific api's you need to look at something non-standard. A great choice is the Qt framework, which provides many tools similar to what is found in the Java libraries, is cross platform, and works well with native C++ idioms.
C++ has a standard library.
You can try reading the "The C++ Standard Library: A Tutorial and Reference". While I don't own it myself, it's on our book list (which I recommend you check out), so it shouldn't be bad.
Note C++ isn't Java, so the libraries don't necessarily have the same functionality. Another resource you'll want to look at is Boost, which serves as a source for well-written C++ libraries for things the standard library lacks.
GNU C++ Standard library documentation is the one I refer to most often.
Java is a virtual machine language and as such attempts to have a comprehensive api to provide a platform independent method of drawing/wrtinging to files / anything. IN the guts of JRE they are taking these generic inputs and using them to do platform specific things. In C++ you are the one that does that work. Many c++ libraries are platform specific see MFC, ATL or code that is written for XWindows it your job to decide how you want to implement a feature and see if that is a platform specific feature or can be done in a platform independent manner.
If you are writing on windows or unix I can assure that the OS API is very complete and will allow you to do what ever your trying to accomplish. Also take a look at cross platfom libraries like lib qt.
Java's standard library is aimed at providing ready-to-use functionality, while the C++ standard library is aimed at providing building blocks that aren't defined by the core language. The Boost library has mainly the same orientation as the standard library (with a few exceptions such as image processing). I think the closest you can get to something like Java's standard library is the Poco library.
However, when I tried on the Poco library I found that it was a bit too C-oriented for my taste.
That is, it's not "modern". You get that impression straight away without even looking at the APIs, because the online docs uses 1990's frames. :-) However, it may fill your needs.
If you mean the c++ standard library I'd look at www.cplusplus.com. It covers the current standards. After familiarizing yourself with that, you could try looking at boost.
There are a number of changes in the upcoming c++0x standard. Wikipedia has info on a number of these as does SO.
The number one book, IMO, for c++ is Effective C++ by Scott Meyers.
I'm coming to C++ from a .Net background. Knowing how to use the Standard C++ Libraries, and all the syntax, I've never ventured further. Now I'm looking learning a bit more, such as what libraries are commonly used? I want to start getting into Threading but have no idea to start. Is there a library (similar to how .net has System.Threading) out there that will make it a bit easier? I'm specifically looking to do Linux based network programming.
For C++, Boost is your everything. Threading and networking are among the things it offers. But there's much more:
Smart pointers
Useful containers not found in the STL, such as fixed-size arrays and hashtables
Closures
Date/time classes
A foreach construct
Min/max functions
Command line option parsing
Regular expressions
As the others have said, Boost is great. It implements the C++ Technical Report 1 in addition to tons of other stuff, including some mind-blowing template metaprogramming tricks.
For other cross-platform features not provided by Boost, I've had very good luck with a library called Poco. I've worked on commercial projects that incorporated its simple HTTP server, for instance, and it treated us quite well.
lots of boost suggestions, but Qt is another good option. It's got great support for threading and networking along with pretty much everything else.
http://qt.nokia.com/products
If you are looking into network programming and are not interested into GUI, I suggest Boost libraries: in particular, Asio.
There's no standard multithreading library, but the boost library includes a platform-independent multithreading abstraction that works very well.
I need to use XmlRpc in C++ on a Windows platform. Despite the fact that my friends assure me that XmlRpc is a "widely available standard technology", there are not many libraries available for it. In fact I only found one library to do this on Windows, (plus another one that claims "you'll have to do a lot of work to get this to compile on Windows). The library I found was Chris Morley's "XmlRpc++". However, it doesn't have support for SSL.
My question therefore is: what library should I be using?
I've written my own C++ library. It's available at sourceforge:
xmlrpcc4win
The reason I wrote it rather than using Chris Morley's was that:
The Windows "wininet.lib" library gives you all the functionality for handling Http requests, so I'd rather use that. As a result, I only needed 1700 LOC.
"wininet.lib", and therefore my implementation, supports HTTPS
Chris Morley's use of STL containers was quite inefficient (Chris, mail me if you read this).
Until I wrote my own library, (see above) here was my answer:
Currently, the XmlRpc++ library by Chris Morley is the only public domain/LPGL XmlRpc implementation for C++ on Windows.
There are a couple of C++ implementations for Linux, either of which could be presumably easily ported to Windows, but the fact seems to be that no-one has yet done so and made it publicly available. Also, as eczamy says, "The XML-RPC specification is somewhat simple and it would not be difficult to implement your own XML-RPC client."
I'm using Chris Morley's library successfully, despite having had to find and fix quite a number of bugs. The Help Forum for this project seems to be somewhat active, but no-one has fixed these bugs and done a new release. I have been in correspondence with Chris Morley and he has vague hopes to do a new release, and he has contributed to this stackOverflow question (see below/above) and he claims to have fixed most of the bugs, but so far he has not made a release that fixes the many bugs. The last release was in 2003.
It is disappointing to me that a supposed widely supported (and simple!) protocol has such poor support on Windows + C++. Please can someone reading this page pick up the baton and e.g. take over XmlRpc++ or properly port one of the Linux implementations.
There are dozens of implementations of the XML-RPC implementations, some in C++, but most in other languages. For example, besides XmlRpc++ there is also XML-RPC for C and C++. Here is a HOWTO on how the XML-RPC for C and C++ library can be used.
The XML-RPC specification is somewhat simple and it would not be difficult to implement your own XML-RPC client. Not to mention, it would also be possible to take an existing XML-RPC implementation in C and bring into your C++ project.
The XML-RPC home page also provides a lot of useful information.
Just wanted to note a couple of items:
The source in the cvs repository for XmlRpc++ has support for OpenSSL (although I have not tried it, it was contributed by another developer).
Most of the reported bugs are fixed in cvs; I don't have access to a linux machine at the moment, so I haven't made an official release.
XmlRpc++ is not public domain. It is copyrighted and licensed (LGPL).
Thanks,
Chris Morley
I was able to get Tim's version of xml rpc working with https and with basic username / password authentication.
For the authentication:
1) the username and password need to be passed to the InternetConnect(...) function
2) an http request header of "Authorization: Basic base64encoded(user:pass)" needs to be added prior to sending the HttpSendRequest(...) command.
(mingw32, windows xp)
Hello, I am attempting to migrate from Java to c++. I am confused and frustrated about finding, installing, and compiling non-standard c++ libraries. in Java it's so convenient they stuffed every functionality and documentation ever needed in java's standard api. Is there a list of essential c++ library such as Threading, gui, networking, image\ audio processing, xml, etc.etc. in one place? or possibly, offered as a single package?
I tried installing QT library for weeks and it wont even compile. in Java i used to learn by trial-and-error to learn new aspect of functionality, but that would be impossible if i can't fetch and run new api in the first place.
please, i need your suggestion, originally i wanted to break free of Java's abstraction, but now i just want to be able to use c++ before I decided shooting myself in the head.
The C++ standard library is extremely light. It contains nowhere near the functionality offered by the Java runtimes or by the .NET CLR.
The Boost libraries add a whole bunch of functionality to C++, but not much (if any) in the area of user interface.
For UI, there's the question of which platform you're targetting. If it's Win32, then you can use the straight Win32 API (mostly designed for C, but there are some C++ wrappers for parts of it). If you want cross-platform, then you're looking at QT or GTK (although there are others).
But, as Andrew already said: "why do you want to learn C++ anyway?". Don't get me wrong: I program in C++ for a living, and actually enjoy it (although I'm beginning to suspect a case of Stockholm Syndrome). If I had to start again, I'd go with a more modern language and environment (Java or C#; or Ruby or Python).
My advice would be: take it one step at a time.
First, figure out how to include a pre-built library in your code. I'd recommend starting with ZLib (it's got a very easy design to work with and it's also a useful tool to have available). Once you've got the pre-built library working, remove it and try compiling ZLib from the source code. Ask on Stack Overflow if you need help at any point, we'll get you through it.
By the time you get that working, you should have all the knowledge you need to get Qt compiled and installed too.
Threading, XML, Networking, some image generation, encoding and processing - boost provides those. As for XML, there's for example Arabica - it abstracts away platform-specific libraries by wrapping them with a nice standard C++ scent.
The GUI part is a different problem.
There's Qt, wxWidgets, gtk with c++ bindings (gtkmm), native libraries for each platform and their C++ wrappers (WTL is an excellent library for Win32), but as the C++ standard evolved and boost is becoming part of the standard (C++0x coming soon), there are no GUI frameworks that leverage those standard facilities and introduce their own instead. They do their job very well though.