Getting started with C and C++

I’ve been learning C and C++ recently and I thought I’d share my experience learning these languages through a post. Prior to learning C and C++, I had experience in Python and Matlab, but this was my first foray into lower level languages. In my attempts to learn each language I made my way through several courses and books available online; some I found very helpful, others not so much. In this post I’ll detail my experiences with each resource and provide some tips that may help those planning on learning these languages.

Main takeaways

To learn the languages, I used four main resources. Online courses from Lynda.com, a book titled Learn C the Hard Way, a book commonly known as K&R 2 and tutorials from cplusplus.com. For those who do not have the time or desire to read this whole post, I found the following resources to be the most useful:

For C:

Learning C the Hard Way

K&R 2

For C++:

Foundations of Programming: Object – Oriented Design (you need a lynda.com login             to access)

Up and Running with C++ (again, you need a lynda.com login to access)

cplusplus.com

Everyone’s learning style is different, but I found that I learned the languages much faster by coding examples myself, rather than watching someone walk through a script. I also found that courses that taught straight from the command line were more effective than courses that taught through an IDE. When using an IDE, I often found myself spending more time working through glitches or nuances within the IDE than learning the languages themselves.

I’ll detail my experiences with each resource below. I’ll start with C resources, then discuss C++.

Resources for Learning C

C Essential Training – From Lynda.com

I started my training by taking course on Lynda.com titled “C Essential Training”. Lynda.com is an online educational website with thousands of videos, many of which focus on programming. The service is free to Cornell students and graduate students (though I checked and unfortunately neither PSU, UC Davis nor CU Boulder have agreements with the site). I found the course to be well structured and I felt that the instructor presented the material clearly and understandably. Despite this, I do not feel that the course did an effective job teaching me C. The main problem I had with the course was its reliance on the Eclipse IDE.  Eclipse seems like a fine IDE, but I don’t plan to use an IDE when writing code and I didn’t want to spend the time taking a separate course to learn its intricacies (though Lynda.com does have a full course devoted to Eclipse). Throughout the course, I kept finding myself having small Eclipse problems (e.g. not being able to change the project I was working on or having compiler errors) that were not hard to solve, but were never discussed in the lectures. I was able to solve each problem by doing some research online, but each little problem took me time to resolve and was mentally taxing. After spending 30 minutes looking up an Eclipse fix, I was not in the mood to go troubleshooting interesting C questions . Another problem with using Eclipse is that the user is never forced to write their own makefiles, an omission that seems like it could really hurt someone who plans to run C programs through the command line. In summary, I would not recommend taking this course unless you are either thoroughly versed in Eclipse or plan to write all of your code through Eclipse.

Learning C the Hard Way

The next resource I used to learn C was a book that Jazmin pointed me to called Learning C the Hard Way by Zed A. Shaw (after some poking around I found this had been mentioned previously on this blog). The book is laid out as a tutorial, where each chapter teaches a new C concept (it’s really a C course in book form).The author takes a slightly nontraditional teaching approach in that he makes you write the code first, then explains in detail what you just wrote. I found this very hands on teaching method extremely helpful. When I wrote the code myself, I was forced to focus on every detail of the code (something that is very important in a language like C). I also was able to learn which concepts were genuinely challenging for me and which concepts I needed more work on. When I watched the Lynda.com lectures, I’d often believe I understood a concept, only to find out later that I had misinterpreted the instructors lesson.

The book does not use an IDE, but rather writes code in a text editor (I used Sublime Text) and runs them on the Unix command line.  The author provides a succinct introduction to makefiles and how to use them, which was refreshing after the Eclipse based course that never mention makefiles or compilers.

Overall I found the teaching method employed by the book to be very effective, and I would highly recommend it to new C users. I should note however, that there seems to be some controversy surrounding the book. If you google “Learning C the hard way” you’ll find some very heated exchanges between the author and a blogger who criticized the book’s teaching methodology. The blogger had two main criticisms of the book; first that it over simplified and inaccurately presented key C concepts, and second, that the author failed to teach accepted programming standards for the C language. Mr. Shaw’s rebuttal was that the book’s purpose was to teach people get people comfortable with C and begin actually coding with it, then  once they are literate, have them go back and learn more about the language’s nuances. I personally agree with Mr. Shaw on this point, though I don’t have a background in computer science so my opinion is only that of an beginner. Many of the criticisms of the book seemed to come from the perspective of an advanced coder who is unable to see the language through the eyes of a beginner. Mr. Shaw’s explanations might be over simplified, but they do a good job demystifying many of the most foreign  aspects of C. I think that use of this book should be supplemented with other sources, especially documents on accepted C coding standards, but if you’re looking for a quick way to get on your feet with C and gain some confidence, then the book is a great resource.

I used a free beta version of the book which can be found here: http://c.learncodethehardway.org/book/ but you can also purchase the book from the author here: https://www.amazon.com/Learn-Hard-Way-Practical-Computational/dp/0321884922

I found the beta version to be just fine, but there were some minor errors and some sections were clearly under construction.

The blog post criticizing the book can be found here: http://hentenaar.com/dont-learn-c-the-wrong-way

K&R 2

A resource that I discovered through reading the exchanges between the Shaw and his critics was “The C Programming Language” by Brian W. Kernighan and Dennis M. Ritchie (commonly referred to as K&R 2 which is what I’ll call it for the rest of the post). One of the Authors of this book, Dennis Ritchie, actually coauthored the C language and this book is talked of as the go to authority of all matters C. Mr. Shaw devoted a whole chapter of “Learning C the Hard way” to bashing this book, but I found its layout and explanations quite accessible and useful. I did not find the tutorials as direct as “Learning C the Hard Way”, but I found it to be a helpful supplement.

 

Resources for Learning C++

Foundations of Programming: Object-Oriented Design – From Lynda.com

A main difference between C and C++ is that C++ is an object oriented language. I had some very basic experience in using object oriented programming, but was looking for a refresher before learning C++. “Foundations of Programming: Object-Oriented Design” was an excellent course that taught me all I wanted to know about object-oriented programming and more. The course is purely conceptual and does not teach any actual code or contain any practice problems. It presents the concepts in a simple yet comprehensive manner that I found very helpful. I would highly recommend this course to anyone hoping to learn or brush up their knowledge of how object-oriented programming works.

Up and Running with C++ – From Lynda.com

This course was very similar in layout to the C course from Lynda.com, and I have the same criticisms. The entire course used Eclipse, and I kept having minor problems that were never addressed by the lectures but prevented me from executing my code. I did feel like I was able to learn the basic tools I needed from the lectures, but I would have gotten much more out of the class if it had been taught through the command line. I also felt that the course was sparse on exercises and heavy on lectures. I found that I got much less out of watching the instructor write code than being forced to write out the code myself (as Learning C the Hard Way forces you to do).

cplusplus.com

This resource is linked often in older posts on this blog, and I found it helpful in answering C++ questions I had after finishing the Lynda.com courses. I did not find that tutorial had the most helpful narration of how one may learn C++ from scratch, but it has very succinct definitions of many C++ components and was helpful as a reference. I think this site is the one I will look to most when troubleshooting future C++ code.

Final thoughts

I’d like to note that I found WRASEMAN’s post on makefiles a few weeks back  to be quite helpful. From my limited experience, ensuring that your code compiles correctly can be one of the most challenging parts of using a lower level language and the post has some excellent resources that explain makefiles are and how they can be used.

I know there are a lot of contributors and readers of this blog who are much more versed in C and C++ than I am, so if you’d like to chime in on useful resources, please do so in the comments.

 

Setting up Eclipse for C/C++

IDEs are tools to make code development a lot easier, specially if your project has multiple files, classes, and functions. However, setting up the IDE can sometimes be as painful as developing complex codes without an IDE. This post will present a short tutorial about how to install and configure Eclipse for C/C++ on Windows 7 in a (hopefully) fairly painless manner. This tutorial is sequenced as follows:

1. Installation
   1. Downloading the Java Runtime Environment.
   2. Downloading the GCC compiler.
   3. Downloading Eclipse.
2. First steps with Eclipse
   1. Setting up a template (optional)
   2. Creating a new project
   3. Including libraries in your project

INSTALLATION

Downloading the Java Runtime Environment

To check if you have the Java Runtime Environment installed, go to java.com with either Internet Explorer or Firefox (Chrome will block the plugin) and click on “Do I have Java?”. Accept running all the pluggins and, If the website tells you you do not have java, you will have to download and install it from the link displayed on the website.

Downloading the GCC compiler

After the check is done, you will have to download the GCC compiler, which can be done from http://www.equation.com. On the side menu, there will be a link to Programming Tools, which after expanded shows a link to Fortran, C, C++. Click on this link and download the right GCC version for your system (32/64 bit), as shown in the following screenshot.

After downloading it, double click on the executable, accept the licence, and type “c:\MinGW” as the installation directory. This is important because this is the first folder where Eclipse will look for the compiler in your computer. Proceed with the installation.

Downloading Eclipse

Now it is time to download an install eclipse. Go to the Eclipse download website and download Eclipse IDE for C/C++ Developers. Be sure to select the right option for your computer (Windows, 32bit/64bit), otherwise eclipse may not install and even if it does it will not run after installed. If unsure about which version you should download, this information can be found at Control Panel -> System by looking at System type.

After downloading it, extract the file contents to “C:\Program Files\eclipse” (“Program Files (x86) if installing the 32 bits version) so that everything is organized. Note that for this you will need to start WinRAR or any other file compression program with administrative privileges. This can be done by right clicking the name of the program on the start menu and clicking on Run as Administrator.

Now, go to C:\Program Files\eclipse and double click on eclipse.exe to open eclipse. In case you get an error message saying, among other things:

Java was started but returned exit code=13
...
...
-os win32
-ws win32
...

then delete the whole eclipse folder, go back to the eclipse download page, download eclipse 32 bit, and extract it as previously described. You should not see the same error again when trying to run eclipse.exe.

Now that Eclipse is up and running, it is time to use it.

FIRST STEPS WITH ECLIPSE

The first thing eclipse will do is ask you to choose a workspace folder. This is the folder where all your code projects will be stored. It should not matter too much which folder you choose, so using the default is probably a good idea.

Setting up templates (optional)

It is helpful to create a code template in order to avoid retyping the same standard piece of code every time you create a new file or project. Many scientific codes have similar imports (such as math.h and stdio.h) and all of them must have a main method (as any C++ code). If we create a code template with a few common imports and the int main function, we can just tell Eclipse when creating a new project to add these to a new .cpp file.

In order to create the mentioned template, go to Window -> Preferences. There, under C/C++ -> Code Style on the left panel, click on Code Templates. Under Configure generated code and comments, expand Files -> C++ Source File, and then click on New. Choose a meaningful name for your template (I chose “Cpp with main”) and type a short description. After that, copy and paste the template below under “Pattern”.

/*
File: ${file_name}

Author: ${user}
Date: ${date}
*/

#include <iostream>
#include <string>
#include <math.h>
#include <stdio.h>
#include <string.h>

using namespace std;

int main()
{
    // Your code here.

    return 0;
}

Note ${file_name}, ${data}, and ${user} are variables, which means that they will be replaced by your file’s actual data. To see a list of the other variables that can be inserted in your template, click on Insert Variable…. Click Ok and Ok again and your template will be ready to be used!

Creating a new project

Click on File -> New -> C++ Project. Under Project type choose Empty Project, then under Toolchains choose MinGW GCC, and, finally, type “project1” as your project name an click on Finish.

After your project is created, click on File -> New -> Source File. Type “say_something.cpp” (no quotes and do not forget the .cpp after the file name) as the name of your source file and choose the template you created as the template. The window should then look like this:

Click on Finish. If you used the template, replace the comment “// Your code here.” by “cout << “Yay, it worked!” << endl;”. Your code should look like the snippet below. If you have not created the template, just type the following code to your file.

/*
File: say_something.cpp

Author: bct52
Date: Jun 26, 2015
*/

#include <iostream>
#include <string>
#include <math.h>
#include <stdio.>
#include <string.h>

using namespace std;

int main()
{
    cout << "Yay, it worked!" << endl;

    return 0;
}

Now, build the code by clicking on the small hammer above the code window and, after the project is built, click on the run button (green circle with white play sign in the center). If everything went well, your window should look like the screenshot below, which means your code compiled and is runs as expected.

Including libraries in your project

When developing code, often times other people have had to develop pieces of code to perform some of the intermediate steps we want our code to perform. These pieces of code are often publicly available in the form of libraries. Therefore, instead of reinventing the wheel, it may be better to simply use a library.

Some libraries are comprised of one or a few files only, and can be included in a project simply by dragging the file into the Eclipse project. Others, however, are more complex and should be installed in the computer and then called from the code. The procedure for the latter case will be described here, as it is the most general case . The process of installation and usage of the Boost library with MinGW (GCC) will be used here as a case study.

The first step is downloading the library. Download the Boost library from here and extract it anywhere in your computer, say in C:\Users\my_username\Downloads (it really doesn’t matter where because these files will not be used after installation is complete).

Now it is time to install it. For this:

1. Hold the Windows keyboard button and press R, type “cmd”, and press enter.
2. On the command prompt, type “cd C:\Users\bct52\Downloads\boost_1_58_0” (or the directory where you extracted boost to) and press enter.
3. There should be a file called bootstrap.bat in this folder. If that is the case, run the command:

   bootstrap.bat mingw

4. In order to compile Boost to be used with MinGW, compile Boost with the gcc toolset. You will have to choose an installation directory for Boost, which WILL NOT be the same directory where you extracted the files earlier. In my case, I used C:\boost. For this, run the command:

   b2 install --prefix=C:\boost toolset=gcc

   Now go read a book or work on something else because this will take a while.

Now, if the installation worked with just warnings, it is time to run a code example from Boost’s website that, or course, uses the Boost library. Create a new project called “reveillon” and add a source file to it called “days_between_new_years.cpp” following the steps from the “Creating a new project” section. there is no need to use the template this time.

You should now have a blank source file in front of you. If not, delete any text/comments/codes in the file so that the file is blank. Now, copy and paste the following code, from Boost’s example, into your file.

 /* Provides a simple example of using a date_generator, and simple
   * mathematical operatorations, to calculate the days since
   * New Years day of this year, and days until next New Years day.
   *
   * Expected results:
   * Adding together both durations will produce 366 (365 in a leap year).
   */
  #include <iostream>
  #include "boost/date_time/gregorian/gregorian.hpp"

  int
  main()
  {
    
    using namespace boost::gregorian;

    date today = day_clock::local_day();
    partial_date new_years_day(1,Jan);
    //Subtract two dates to get a duration
    days days_since_year_start = today - new_years_day.get_date(today.year());
    std::cout << "Days since Jan 1: " << days_since_year_start.days()
              << std::endl;
    
    days days_until_year_start = new_years_day.get_date(today.year()+1) - today;
    std::cout << "Days until next Jan 1: " << days_until_year_start.days()
              << std::endl;
    return 0;
  };

Note that line 9 (“#include “boost/date_time/gregorian/gregorian.hpp””) is what tells your code what exactly is being used from Boost in your code. Line 15 (“using namespace boost::gregorian;”) saves you from having to type boost::gregorian every time you want to use one of its functions.

However, the project will still not compile in Eclipse because Eclipse still does not know where to look for the Boost library. This will require a couple of simple steps:

1. Right click on the project (reveillon), under the Project Explorer side window, then click on Properties. Under C/C++ Build->Settings, click on Includes under GCC C++ Compiler. On the right there should be two blank boxes, the top one called Include paths (-I) and the other called Include files (-include). Under Include paths (top one), add the path “C:\boost\include\boost-1_58” (note that this path must reflect the path where you installed Boost as well as which version of Boost you have). This is where the compiler will look for the header file specified in the code with the #include statement.
2. The compiled library files themselves must be included through the linker. This step is necessary only if you are using a compiled library. For this, on the same window, click on Libraries under MinGW C++ Linker. Add the path to the Boost libraries folder to the Library search path (-L) (bottom box). this path will be “C:\boost\lib” (again, if you installed Boost in a different folder your path will be slightly different). Now the actual compiled library must be added to the Libraries (-i) (top box). First, we need to figure out the name of the compiled library file used in the code. In this case, it is the file “libboost_date_time-mgw51-mt-d-1_58.a”. Therefore, add boost_date_time-mgw51-mt-d-1_58 (no lib prefix, no .a postfix, and be sure to match the name of your file) to Libraries (-i). Click Ok and Ok again.

Now compile the code by clicking on the hammer button and run the rode by clicking on the play button. Below is a screenshot reflecting both steps above as well as the expected output after running the program.

That’s it. After your model is in a good shape and it is time to run it with Borg (or other optimization algorithm), just change your “int main()” to a function with your model’s name and the right Borg’s arguments, add the standard Borg main, and change the makefile accordingly. Details on how to do all this for Borg will be explained in a future post.

Setting up Python and Eclipse

According to its website, Python is:

…an easy to learn, powerful programming language. It has efficient high-level data structures and a simple but effective approach to object-oriented programming. Python’s elegant syntax and dynamic typing, together with its interpreted nature, make it an ideal language for scripting and rapid application development in many areas on most platforms.

The Python interpreter and the extensive standard library are freely available in source or binary form for all major platforms from the Python Web site,http://www.python.org/, and may be freely distributed. The same site also contains distributions of and pointers to many free third party Python modules, programs and tools, and additional documentation.

This post covers how to set up Python and the Eclipse development environment.  We also provide a collection of posts on how to use Python for data analysis, starting here.

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PYTHON:

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The first step is to download Python and its various packages that will likely be useful to you at some point.

Python itself is available at: http://www.python.org/download/

I would recommend downloading and installing version 2.7.2, the latest production release under the 2.X series.  Also, stick with the 32-bit version as most all packages will be available for this version.  Avoid Python 3.X for now.  It is not as widely supported among the various Python packages that you might find useful and as such, should be avoided for now.  Keep in mind that there are some syntax differences as well between versions 2.X and 3.X that would need to be addressed whenever it does come time to update.

Just use the default settings during installation.

NOTE: If you have Cygwin installed on your system, it too has likely installed a version of Python.  Whenever you run Python from the command line, you should be careful to ensure that you are using the version that you expect (i.e., the default Cygwin installed Python versus the one that you installed).  Just be aware of this.  In general, it is easy to identify the version being picked up from the path name.  Also, it is generally best to use the version that you have installed.  It will usually be located in C:\Python27 whereas the Cygwin version will be located in C:\Cygwin\bin.

Now, install the various packages that may be useful. You should always be careful to install a version of the package that matches your version of Python (i.e., 2.7 if you are following my instructions).  Sometimes, if a package is not available for the version you are using (i) you may still be able to use it, or (ii) you may need to make minor tweaks to the package source to get things running. Also, always download the package installers, not the source.  Here are the common ones that you should definately install:

• NumPy and SciPy available at http://numpy.scipy.org/.  These packages are useful for performing scientific computing within Python.  Download the “win32 superpacks” for each of these packages for the version of Python that you have installed.
• PIL – the Python Imaging Library available at http://www.pythonware.com/products/pil/.  This package is useful to manipulating image files.
• matplotlib – a 2D plotting library with Matlab-like syntax available at http://matplotlib.sourceforge.net/.  This package is very good for creating good publication quality figures.  If you starting using it, you will probably notice that the appearance of the figures, even on-screen, is much improved over what Matlab can produce.

The following are some optional packages based on your particular needs:

• Py2exe – a package for bundling Python scripts into MS Windows executable programs available at http://www.py2exe.org/.  This is what I use to bundle all of the libraries and source code required by AeroVis into a self contained package that can be installed on any Windows system without the need to build or install Python, VTK, Qt, etc.
• wxPython – GUI package for Python available at http://wxpython.org/.  Note, this is for developing graphical user interfaces (GUIs) for your Python scripts, it is not a GUI for Python.
• PyQt – another GUI package for Python available at http://www.riverbankcomputing.co.uk/software/pyqt/intro.  PyQt is a set bindings for Nokia’s Qt application framework – a very rich and full featured graphical interface development framework.  AeroVis uses PyQt for its graphical interface.

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ECLIPSE:

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Now that you have Python and all of your needed packages installed, you can now move on to Eclipse. Eclipse is available from http://www.eclipse.org/downloads/packages/release/indigo/r.  The latest release (and probably the version you should be using) is Indigo.  Since we primarily use Visual Studio for C/C++ development, I would recommend downloading the IDE for Java as this will serve to provide you with a Java environment should you choose to explore this down the road.  I think you should be able to install either the 32-bit or 64-bit versions without issue.  Just make sure you are running a 64-bit OS if you choose to install that version.  When you go to download, Penn State actually has a mirror so choose this.  BTW, don’t choose the BitTorrent option – not a good idea on PSU networks.

Once you have downloaded the zip file containing Eclipse, you just unzip it wherever you want it to be installed.  This includes portable drives etc.  The beauty of Eclipse is that unlike many Windows programs, it is completely self contained and as such, can be run from any location.  Once unzipped, create a shortcut to the Eclipse executable and start it up.

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PYDEV:

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Now that Eclipse is installed, we can add a Python development environment inside Eclipse that will provide a very nice Python IDE with debugging capabilities, etc.

The install for packages inside Eclipse proceeds a little differently than what you may be used to.

The best option for installing PyDev is probably to install Aptana Studio which includes a variety of development tools.  Go to this site for instructions http://www.aptana.com/downloads/start or read on.

1) In the Eclipse Help menu, select Install New Software
2) Paste this URL into the Work With box: http://download.aptana.com/studio3/plugin/install
3) Check the box for Aptana Studio and click Next
4) Accept the license, etc., and restart Eclipse

Another option is to only install PyDev from within Eclipse, carefully follow the instructions available at: http://pydev.org/manual_101_install.html.  There’s no need for me to rehash all of these instructions here as they are quite good at the PyDev site.

Once PyDev is installed, you should be ready to go.

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Let me know if you run into any problems by leaving a comment.

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Up Next Time…

Developing and debugging Python scripts and projects in Eclipse