Creating and building ros worksapce in QT creator?

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Many Thanks...When I changed the build system to CatkinMake, the CMakeLists.txt appears inside src, But it does not appear in the QT Creator's project view hierarchy (at the left of QT Creator). I tried to right click src folder ==> Add existing file ==> select CMakeLists.txt, But it is also not shown in the project view.

Also, in the Terminal, when I run the command echo $ROS_PACKAGE_PATH, my workspace is not shown as the first one. I also created a new package under the src, But nothing appear under src even though include,src, package.xml, CMakeLists.txt physically exist in the folder.

For the issues with missing files and directories, closing and reopening the project within Qt Creator. I've noticed that it sometimes does not dynamically add new files and directories to the project view (for example, when cloning in a new package repository).

For the issue with ROS_PACKAGE_PATH, did you source the newly-built workspace from the terminal?

For ROS_PACKAGE_PATH, many thanks, it works after sourcing

If I close the project: File => close project.

Then, File => Open File or Project ==> which file I have to choose to open the project?

If your project is listed under the File => Recent Projects, you can re-open it that way. From the "Open File or Project" menu, you need to select the .workspace file at the top level of your workspace. For example, one of mine is located at ~/melodic_ws/melodic_ws.workspace.