ROS C++

Comparing C and C++ Programming Rules

• C and C++ are related programming languages, with C++ being an extension of C.

• While they share many concepts and syntax elements, C++ introduces additional features and paradigms, such as object-oriented programming (OOP).

• Here are some key differences:

1. Object-Oriented Programming (OOP):

   • C++ supports OOP with features like classes, objects, inheritance, and polymorphism, allowing for more organized and modular code.

   • C does not directly support OOP; it relies on procedural programming.

2. Classes and Objects:

   • C++ allows the creation of classes to encapsulate data and methods into objects.

   • C does not have classes or built-in support for objects.

3. Standard Template Library (STL):

   • C++ provides the STL, which includes ready-to-use containers (like vectors, maps, and queues) and algorithms.

   • C does not have a built-in STL.

4. Namespaces:

   • C++ has namespaces to avoid naming conflicts and provide better organization of code.

   • C does not have namespaces.

5. Function Overloading:

   • C++ supports function overloading, which allows multiple functions with the same name but different parameter lists.

   • C does not support function overloading.

6. Type Safety:

   • C++ offers stronger type safety through features like the static_cast operator and type-safe template classes.

   • C has fewer type safety features.

Creating a ROS C++ Package

• To create a ROS package using C++, follow these steps:

  • Open a terminal and navigate to your ROS workspace directory.

  • Create a new ROS package using the catkin_create_pkg command, specifying the package name and any dependencies. Include roscpp as a dependency for C++ programming:

    catkin_create_pkg my_cpp_package roscpp rospy std_msgs
    

  • Navigate to the package directory:

    cd my_cpp_package
    

  • Create a src directory to store your C++ source code:

    mkdir src
    

  • Inside the src directory, you can start writing your C++ nodes using ROS APIs and C++ programming.

ROS C++ Build Settings

• ROS uses Catkin as its build system. Here’s how to configure your ROS C++ package’s build settings:

  • Open the CMakeLists.txt file located in your package directory.

  • Add the following lines to find the required ROS packages and set the compiler flags:

    find_package(catkin REQUIRED COMPONENTS
        roscpp
        rospy
        std_msgs
    )
    
    catkin_package()
    
    include_directories(
        ${catkin_INCLUDE_DIRS}
    )
    

  • For each C++ node you create, add an executable target in your CMakeLists.txt:

    add_executable(my_cpp_node src/my_cpp_node.cpp)
    target_link_libraries(my_cpp_node ${catkin_LIBRARIES})
    

  • Build your package using the following commands:

    catkin_make
    

  • This command compiles your package’s code and generates the necessary executables and libraries.

  • Creating a ROS C++ package involves configuring CMake for your project, creating C++ nodes using ROS APIs, and using catkin_make to build your code.

  • If your projects become more complex, you might need to handle additional dependencies, custom messages, and more sophisticated build configurations.