Thread: How does one analysis difficult code and track variable manipulations in C++?

I started reading Bjarne Stroustrup C++ Programming Practises and Principles. Recently I have been stuck on Chapter 6 and 7 with the Parser 'Simple Calculator' program the book was teaching.

When analysing abstract programs its hard to know how functions and objects manipulate input streams and where it sends them after. In this book when he introduced parsing there are times when an object function calls a object where that object calls a recursion, where that recursion calls another method that calls two separate recursions.... it makes you wonder to yourself how you managed to learn and understand the derivation of the Gravitational Constant g but a simple calculator

In V.S.I heard you can use the debugger and toggle checkpoints but there has to be a more efficient way when:

You don't know where the code is going...


Here it is:
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My question is ~ how can I better analysis and keep track of the variable values of the input stream >> output stream. If you can help me use the debugger for such complexity I guess the question wont be opinion based..

I know it's lame but I really like using print flags.