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Notice: This page contains information for the legacy Phidget21 Library.

Phidget21 is out of support. Bugfixes may be considered on a case by case basis.

Phidget21 does not support VINT Phidgets, or new USB Phidgets released after 2020. We maintain a selection of legacy devices for sale that are supported in Phidget21.

We recommend that new projects be developed against the Phidget22 Library.


Click on the 2phidget22.jpg button in the menu bar to go to the Phidget22 version of this page.

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Language - C

From Phidgets Legacy Support
Revision as of 17:48, 14 November 2011 by Cora (talk | contribs)

Support

C/C++ has a complete API and sample code for all Phidgets devices. You can also view a complete list of the status for our supported languages.

If this is your first time working with a Phidget, we suggest starting with the Getting Started page for your specific 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++ can be developed with various Windows compilers (including Borland), Mac OSX, and Linux.

Quick Downloads

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

C/C++ API Documentation:

C/C++ Example Code:

Libraries and Drivers:

Getting Started (Windows)

Running Examples

A good way to learn to use Phidgets 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 within the example package. 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

The Phidget examples were written using Visual C++ 2005. They also work well in other similar environments such as Visual Studio.

Specific setup for many other common compilers is covered below. Often, you can just import the example as an existing project, but if you are having trouble it might help to read the Developing Code section below for your specific compiler.

Following the Examples

You can learn about the flow within the examples by reading about General Phidget Programming, which will walk you through the concepts in each example, regardless of your device.

The examples for each device all have this general structure so you can follow along:

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

  

{{{1}}}

// ----- 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

 

{{{2}}}

Writing Your Own Code (Windows)

You can use a Phidget in code by essentially by:

  1. Opening it,
  2. Setting it up,
  3. Doing things with it (like reading data), and
  4. Closing it.

These steps are generally outlined for all devices and languages on the General Phidget Programming page, and demonstrated in the examples above. The General Phidget Programming page also introduces using the Phidget in an event-driven manner and in a traditional manner, both of which are available in C/C++.

The complete set of functions you have available for all Phidgets can be found in the C/C++ API.

If you are looking for more information about a particular function, we provide that as well. You can find more description on any function either in:

  1. Our API Overview which describes the set of calls common to all Phidgets, or
  2. The Device API page for calls available only on your specific Phidget.
These Windows sections below need additional information

General Windows Library Setup

In addition to actually creating code to drive your Phidget, you will also need to properly link the Phidget C/C++ libraries, which are included with the drivers above. Most compilers provide their own documentation on how to link external libraries. (Note that for Borland, you'll need a different library, which you can find in the Borland section below).

Then, in your code, you usually need to include the Phidget library specifically: 

  #include "phidget21.h"

Visual C++ 2005 Library Setup

To link libraries in Visual C++ 2005:

  • Generate a new C/C++ console project with a descriptive name such as PhidgetTest.
  • Copy phidget21.h and phidget21.lib from the VC/VC++/Borland examples and add them to your project directory.
  • Open the project properties window.
  • Navigate to Configuration Properties | Linker | Input.
  • Edit the additional dependencies and add “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:

Creating Your Project

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

C/C++ API Documentation:

Build and compile your project with the properly linked

Getting Started (MacOS/Linux)

Setting up the Libraries

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

  #include <phidget21.h>

Afterwards, the Phidget object will need to be declared and then initialized. For example, we can declare a software object to use a Phidget Interface Kit inside our main function with: 

  int main(int argc, char* argv[])
  {
    CPhidgetInterfaceKitHandle device = 0;
    CPhidgetInterfaceKit_create(&device);
    //More code goes here
    return 0;
  }

The object name for any type of Phidget is listed in the API manual. Every type of Phidget also inherits functionality from the Phidget base class.

Developing Code (Mac OSX/Linux)

Running Examples

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, as above
  • Go from source code to a test application as quickly as possible

Writing Your Own Code

You can use a Phidget in code by essentially by:

  1. Opening it,
  2. Setting it up,
  3. Doing things with it (like reading data), and
  4. Closing it.

These steps are generally outlined for all devices and languages on the General Phidget Programming page. The General Phidget Programming page also introduces using the Phidget in an event-driven manner or in a traditional manner, both of which are available in C/C++.

The complete set of functions you have available for all Phidgets can be found in the C/C++ API.

If you are looking for more information about a particular function, we provide that as well. You can find more description on any function either in:

  1. Our API Overview which describes the set of calls common to all Phidgets, or
  2. The Device API page for calls available only on your specific Phidget.

Compiling Your Program

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

Building your Project

Describe the different ways a project could be built and packaged using this language.

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 section in the Getting Started (Windows) section above. If it can be covered by a combination of the Getting Started section above, and the Common Problems section below, delete this section...

Common Problems and Solutions/Workarounds

Here you can put various frequent problems and our recommended solutions.

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