Any definable types, do not need classes. It is done with some non-standard extensions by some C compilers ...
Well, if it is done with "non-standard extensions" then it is not C anumore now is it.
So it does not require any classes. We already have user data types in C and that is all that is needed.
Really? Please demonstrate how.
In the current problem we need to perform arithmetic on arbitrarily big integers, up to a million digits. We need to define operators on that number type, add, subtract, multiply...
So, firstly we need to be able to declare them in a similar way to regular variables in C, for example:
The we need to be able to do arithmetic on them in the same way we would with C variables, for example:
There is no way to do that in C. If you claim that there is then please show an example.
Perhaps if you do operator overloading the old fasioned way (from when C++ was in its infancy), using an operator type function instead of a class method? May simplify life a little.
Please show a simple example of what you mean. An example that we can compile and run with C++ at least as it has been since the first book on it was published by Stroustrap in 1985.
Interesting how far you fell into the C++ pit on this simple of a task
Like I say, if you have a better way to do it then please do show your working.