TensorFlow provides API to call its modules implemented at a low-level paradigm in C++ class and function. https://www.tensorflow.org/api_docs/cc
The functionality of TensorFlow (TF) is implemented in many languages and one of them is C++,
but Python is used as an interface (front-end) between the backend system and the users.
The TF C++ API is built on TensorFlow Session (in the old version) and TensorFlow ClientSession (in the new version).
One can make use of either of these to execute TensorFlow graphs that have been built using the Python API and serialized to a GraphDef.
The runtime of TensorFlow is written in C++, and mostly, C++ is connected to TensorFlow through header files in tensorflow/cc.
The C++ API is still in the experimental stages of development, and also the documentation is being updated,
meaning that it lacks information and a tutorial about how to use TensorFlow API.