Where can I find complex and detailed examples for training Tensorflow in C++?

I want to build and train a graph in C++ with TensorFlow that consists of two layers, and to feed it with a given matrix as an input.

I didn't find yet any comprehensive tutorial for building a TensorFlow graph and optimize it in C++.

Till now I found only these two relevant code pieces:

An official C++ example without real training nor optimization

An important answer about feed_dict but without examples

Is it possible that the "input" argument for the Session->Run() in the first link has a bug? It does not contain the string "x:0" as suggested in the second link.

Thank you!