I wont be able to create reference to Bag class: undefined reference to `rosbag::Bag::Bag()

edit

The error you quote is basically a linking error, meaning the linker can't find the library that provides the binary code for a particular symbol you use.

This is not a ROS problem.

In this case you're not linking against the rosbag libraries.

You'll need to make sure that you've added rosbag to the find_package(catkin COMPONENTS ..) (or a regular find_package(..)) line in your CMakeLists.txt, and that you've added the appropriate target_link_libraries(..) that links your executable against the rosbag library.

As this is all CMake, you'll want to keep the CMake Documentation at hand.

Edit:

@gvdhoorn I made CMakeLists.txt as you suggested: like below:

cmake_minimum_required (VERSION 2.6)
project (tutorial)
find_package(catkin REQUIRED rosbag)
set(SOURCES sampleOne.cpp)
add_executable(test ${SOURCES})
target_link_libraries(test)

Two things here:

1. if you just need rosbag, there is no need for find_package(catkin ..), just use find_package(rosbag REQUIRED) directly.
2. you have a target_link_libraries(..) in there, but you don't actually link your test binary against any libraries.

The last point is actually why you're still getting errors.

both source code and CMakelists.txt is in a directory named "cmake_example".

Now I ran

cmake .
make

Please don't use in-source builds with CMake.

which does not product executable named "test"

but if I remove first line of source code

rosbag::Bag bag;

it does create executable named "test", which I can happily execute.

Which makes sense, as you're not actually linking against any of rosbag's libraries.

Try the following:

cmake_minimum_required(VERSION 2.6)
project (tutorial)
find_package(rosbag REQUIRED)
include_directories(${rosbag_INCLUDE_DIRS})
add_executable(test sampleOne.cpp)
target_link_libraries(test ${rosbag_LIBRARIES})

That will probably work.