Language - C: Difference between revisions

Revision as of 21:03, 21 December 2011

C++ is a general purpose, cross-platform programming language with a vast user base.

Support

If this is your first time working with a Phidget, we suggest starting with the Getting Started page for your specific device. This can be found in the user guide for your device. That page will walk you through installing drivers and libraries for your operating system, and will then bring you back here to use C/C++ specifically.

C/C++ is capable of using the complete Phidget API. We also provide example code in C/C++ for all Phidget devices.

C/C++ can be developed with various Windows compilers (including Borland, Cygwin, and MinGW), Mac OSX, and Linux.{{{5}}}

You can compare C/C++ with our other supported languages.

Quick Downloads

Just need the C/C++ drivers, libraries, and examples? Here they are:

C/C++ API Documentation:

C/C++ API Manual Download or (HTML online version)
General API (more help on functions common to all Phidgets)
Device Specific APIs (more help on functions specific to your Phidget)

C/C++ Example Code:

Libraries and Drivers:

32 bit Windows (drivers, with libraries)
64 bit Windows (drivers, with libraries)
Borland C++ Libraries (You also need one of the two Windows drivers above)
General Linux Libraries ( Linux Library Setup Instructions)
General Mac OSX Libraries ( Mac OSX Library Setup Instructions)

Getting started with C/C++

If you are new to writing code for Phidgets, we recommend starting by running, then modifying existing examples. This will allow you to:

Make sure your libraries are properly linked
Go from source code to a test application as quickly as possible
Ensure your Phidget is hooked up properly

Instructions are divided up by operating system. Choose:

Windows 2000 / XP / Vista / 7
Linux (including PhidgetSBC)
Mac OS X

Windows

C/C++ programs on Windows depend on three files, which the installers above put onto your system:

Phidget21.dll contains the actual Phidgets library, which is used at run-time. If you used our installer, it's already correctly placed in C:\Windows\System32. It can be manually installed - check our Manual Installation instructions.
Phidget21.lib is used by your compiler to link to the dll. Your compiler has to know where this file is. Our installer puts Phidget21.lib into C:\Program Files\Phidgets -Could be wrong-. Phidget21.lib is written to be compatible with most compilers - but your specific compiler may need a different format. Check our documentation for your specific compiler below for details.
Phidget21.h lists all the Phidget API function calls available to your code. Your compiler also has to know where this file is. By default, our installer puts Phidget21.h into C:\Program Files\Phidgets so you can either point your compiler to that location, or copy and link to it in a directory for your project workspace. We offer some instruction below, by compiler.

Generally, to run the examples, you will download them and unpack them into a folder. If you browse around within the examples, you'll note that the examples are specific to each Phidget. So, you'll need to find the source code for your specific device within the example package.

When you are building a project from scratch, you will need to properly link the Phidget C/C++ libraries described above. Most compilers provide their own documentation on how to link external libraries. For some compilers, such as Borland and Dev C++, you will need to use different libraries. Please check your compiler section below to see if something specific is needed. Then, in your code, you usually need to include the Phidget library specifically:

  #include <phidget21.h>

Visual Studio

Visual Studio 2010

Visual Studio 2008

Visual Studio 2005

Visual Studio 2003

Visual Studio 6

Borland

C/C++ API Reference
Borland C++ Libraries (You also need one of the two Windows drivers above)

GCC on Windows

CygWin

MinGW

Dev C++

These Windows sections below need additional information

General Windows Library Setup

In addition to actually creating code to drive your Phidget,

Visual Studio C++ Library Setup

To link libraries in Visual C++ 2005:

Generate a new C/C++ console project with a descriptive name such as PhidgetTest.
Open the project properties window.
Navigate to Configuration Properties | C/C++
Add "C:\Program Files\Phidgets" to the additional directories field.
Navigate to Configuration Properties | Linker | Input.
Edit the additional dependencies and add "C:\Program Files\Phidgets\phidget21.lib".

The project now has access to the Phidget21 function calls and you are ready to begin coding.

Borland C/C++ Library Setup

To link libraries in Borland C/C++:

Make sure to download the additional Borland-specific libraries in addition to the drivers you already have through the Getting Started page for your device:

Borland C++ Libraries

To compile and link your program: bcc32 -I"C:\Program Files\Phidgets" -L"C:\Program Files\Phidgets" phidget21bcc.lib example.c

MinGW Library Setup

To compile and link your program: gcc example.c -I"C:\Program Files\Phidgets" -L"C:\Program Files\Phidgets" -lphidget21

Cygwin Library Setup

To compile and link your program: gcc example.c -I"/cygdrive/c/Program Files/Phidgets" -L"/cygdrive/c/Program Files/Phidgets" -lphidget21

Dev C++ Library Setup

In order to control Phidgets with Dev-C++, the library file will need to be in a format that Dev-C++ accepts, as described in the following steps. The following steps works with Dev-C++ 4.9.9.2. Download the reimp tool(Please download it here), and type the following command to create libphidget21.a.

reimp.exe "C:\Program Files\Phidgets\phidget21.lib"

Place libphidget21.a in <Dev-Cpp Install Directory>/lib

Open up your project in Dev-C++, and traverse to Project Options->Parameters->Linker, and enter the following to link to the library:

-lphidget21

Next, the path to phidget21.h will need to be specified. Traverse to Project Options->Directories->Include Directories, and add the path to the Phidget installation directory:

C:\Program Files\Phidgets

Mac OSX

One good way to start developing your application is to run and modify existing examples. You can find the C/C++ API and example code here:

To run the example code, you'll need to find the source code for your specific device. Then, compile the code under your platform and run it. This will allow you to:

Make sure your libraries are properly linked
Go from source code to a test application as quickly as possible
Ensure your Phidget is hooked up properly

The examples assume that the compiled libraries have been set up properly. To set them up on Mac OSX, follow the Getting Started page for your specific device

To compile, link the Phidget libraries, and build an executable binary on MacOS, do (for example, depending on the Headers location):

  gcc example.c -o example -framework Phidget21 -I/Library/Frameworks/Phidget21.framework/Headers

After using gcc, you will have an executable named example that you can run.

When writing your code from scratch, you must include a reference to the library header:

  #include <phidget21.h>

Then, you would compile your completed C/C++ code the same way as the examples.

Linux

One good way to start developing your application is to run and modify existing examples. You can find the C/C++ API and example code here:

To run the example code, you'll need to find the source code for your specific device. Then, compile the code under your platform and run it. This will allow you to:

Make sure your libraries are properly linked
Go from source code to a test application as quickly as possible
Ensure your Phidget is hooked up properly

The examples assume that the compiled libraries have been set up properly. To set them up on Linux, compile and install them as explained on the main Linux page

To compile, link the Phidget libraries, and build a binary executable on Linux, do the following in a terminal in the directory with example.c:

  gcc example.c -o example -lphidget21

After using gcc, you will have an executable named example that you can run. On Linux, if you have not set up your udev rules for USB access you will need to run the program as root.

When writing your code from scratch, you must include a reference to the library header:

  #include <phidget21.h>

Then, you would compile your completed C/C++ code the same way as the examples.

Follow The Examples

By following the instructions for your operating system and compiler above, you probably now have a working example and want to understand them better so you can change them.

The Hello World example has this general structure so you can follow along. We also have an in-depth general introduction to writing Phidget code (like open, read data, etc), as well as the {{{3}}} for specific syntax:

// ----- Event and Other Functions ----- Create any Language-Specific Functions (exception handling) Create General Attach, Detach, and Error Handling Functions: On attach: Print Hello Message On detach: Print Goodbye Message		In C/C++, you can name these event functions whatever you like. You will then pass them as function pointers to the Phidget library below in the Main Code section. This hooks them into the actual events when they occur. In the example code, the event functions common to all Phidgets are called things like AttachHandler() and DetachHandler(), etc. Some event functions will be specific to each device, like when a tag is read on an RFID board, or when a sensor value changes on an Interface Kit. Other functions are given in the examples to show you more detail on using your Phidget. For example, DeviceInitialize() will show what needs to be set up for your Phidget before using it.
// ----- Main Code ----- Create Manager Software Object Hook Event Functions created above to Device Open Device Wait for 'Enter' key character input Handle on-going attach and detach events Print Hello and Goodbye messages Exit upon input Close Device Delete Device		Creating a Phidget software object in C is specific to the Phidget. For a Phidget Spatial, for example, this would involve creating an object with the `CPhidgetSpatialHandle` type, and then initializing it using the `CPhidgetSpatial_create` function. The examples show how to do this and other API functions. Other C calls follow a similar syntax - `CPhidgetXXX_function`, where XXX is the name of your device, and function is an action available from the API for your specific Phidget.

When changing the examples to do what you want, or writing your own code, you will probably find these API resources useful because they outline the C/C++ functions that you can use:

C/C++ API (This is the complete set of functions you have available for all Phidgets)
Device Specific APIs - The one for your Phidget can be found in its user guide.

To learn the details behind opening, configuring, using, and closing your Phidget, try the General Phidget Programming page. That page also describes using the Phidget in an event-driven manner and in a traditional manner, both of which are available in C/C++.

Write Your Own Code (Mac OSX/Linux)

C/C++ API (This is the complete set of functions you have available for all Phidgets)
Device Specific APIs - The one for your Phidget can be found in its user guide.

To learn the details behind opening, configuring, using, and closing your Phidget, try the General Phidget Programming page. That page also describes using the Phidget in an event-driven manner and in a traditional manner, both of which are available in C/C++.

General Mac OS/Linux Library Setup

Before you can use the Phidget, you must include a reference to the library header.

  #include <phidget21.h>

Create and Build Your Project

With the libraries linked properly in your compiler, you can consult the following resources for help with writing code:

C/C++ API Manual Download or (HTML online version)
General API (more help on functions common to all Phidgets)
Device Specific APIs (more help on functions specific to your Phidget)

The page with general programming concepts for Phidgets

Compiling and linking against the Phidgets Library can be done in the following ways:

To build on Linux:

  gcc example.c -o example -lphidget21

To build on MacOS (for example, depending on the Headers location):

  gcc example.c -o example -framework Phidget21 -I/Library/Frameworks/Phidget21.framework/Headers

Development Environments and Compilers

Describe each major compiler and notable differences or important information. (eg. framework versions) If there are known issues/workarounds mention them and link to the corresponding issue at the bottom of the page.

This section may or may not be covered in the different compilers sections above in Getting Started (Windows), and the common problems below? If so, delete this section.

Dev C++
In order to control Phidgets with Dev-C++, the library file will need to be in a format that Dev-C++ accepts, as described in the following steps. The following steps works with Dev-C++ 4.9.9.2. Download the reimp tool(Please download it here), and type the following command to create libphidget21.a.

reimp.exe "C:\Program Files\Phidgets\phidget21.lib"