I looked back on my code so far and found that I rarely wrote class. Or, in other words, I don't see the value of using them. I mean, almost everything in coding, I can work them out without using classes by just writing functions and group them into different .h/.cpp files based on their functionalities.
Even after I've participated in several projects, I still do not feel the urgency to do this as progress goes well without big challenges. I am working mostly with C++ (MATLAB sometimes).
Note that, I did use struct a lot and I know that struct and class have no big difference for C++. But I only use struct for data-storage (group data together). The data requires no flow control (i.e. getters/setters that maintain or protect an internal state) nor starts acquiring any major functionality.
Maybe I am missing somewhere about basic things about OOP. So when should we encapsulate our codes using classes? Can anyone share your opinions?
In C++, a struct and a class are just the same except with a different default access modifier. struct members are by default public, whereas class members are by default private. If we think of classes in C++ as being a class with encapsulated data members and public member functions that expose functionality related to that data, the following are some good suggestions that you want to use a class:
If you have only suggestion 1, then you probably just want a struct. See Classes Should Enforce Invariants.