用C++写一段在ros里面把四元素转换成欧拉角的代码

Sure! Here's a sample code in C++ to convert a quaternion to Euler angles in ROS:

#include <ros/ros.h>
#include <tf2/Math/Quaternion.h>
#include <tf2/LinearMath/Matrix3x3.h>

int main(int argc, char** argv)
{
    ros::init(argc, argv, "quaternion_to_euler");
    ros::NodeHandle nh;

    // Create a Quaternion
    tf2::Quaternion quaternion;
    quaternion.setRPY(0.1, 0.2, 0.3);  // Set the roll, pitch, and yaw angles

    // Convert Quaternion to Euler angles
    tf2::Matrix3x3 matrix(quaternion);
    double roll, pitch, yaw;
    matrix.getRPY(roll, pitch, yaw);

    // Print the Euler angles
    ROS_INFO("Euler angles: Roll = %f, Pitch = %f, Yaw = %f", roll, pitch, yaw);

    return 0;
}

In this code, we use the `tf2` library to work with quaternions and perform the conversion to Euler angles. The `setRPY` function is used to set the roll, pitch, and yaw angles of the quaternion. Then, we create a `Matrix3x3` object from the quaternion and use the `getRPY` function to extract the Euler angles.

Remember to compile this code with the appropriate ROS package dependencies and run it within a ROS environment.