Thread: Moving from C to C++

I made the same move earlier this year because of college (did
C last year and C++ was on the course for this year). I did a
quick search on google and i came up with this, the start of
which lists some of the basic differences.

The main things, as i see it, are:

C++ introduces a concept called object orientation. Simply put,
this is the combination of attributes (variables) and methods
(functions) which describe and represent an object. The easiest
and quickest example is modelling a bank account: Attributes
might be the account balance, account holders name, interest
rate, and then methods, which are a way to interact with the
object, such as making a lodgement, cashing a check etc. These
objects involve data encapsulation - the idea that for an object,
the only way to manipulate the attributes is via the methods.

Basically, an object is like a black box - you shouldn't be able to
get into it, you don't know how it does what it does, but that
shouldn't stop you from using it. The advantages of this style of
programming are numerous: It allows companies to design code
that performs logical functions, code becomes more portable,
code can be reused, extended, or shortened, and also,
programmers have more control over how their code is used.

to make a crude comparison that is intuitively accurate from what
i have described, in C speak, an object can be thought of as
having attributes grouped together in a struct, but only a certain
collection of functions are allows modify that stuct - the stuct
will be out of scope as far as all other functions are concerned.
That is OOP in a nutshell.

Features - C++ versus C

C++ is a much more detailed language than C. As above, OOP is
allowed, dynamic memory allocation is greatly simplified, strong
type checking is built in - assignments of incompatible types
produce compilation errors, simplified file I/O, References - a
partial alternative to pointers with a far simpler syntax, improved
string support using the string class (i never mentioned that the
word class is used in C++ when declaring an object - so i did it
here), support for generic programming using the Standard
Template Library (a group of classes that act as "containers" for
any data type - sheer genius), built in error handling mechanisms
(exception handling it's called), namespacing (another part of
breaking code into logical divisions) and last but not least,
inheritance - classes can inherite attributes and functionality
from other classes, and functions can be redesigned as necessary
which allows for a substantial amout of code reuse on large
projects.

Well i said it was a detailed language! The last, probably most
important feature is the fact that because C++ was developed
from C, the C++ language is ALMOST a complete superset of C,
with the exception of a few items that would be legal in C but
illegal in C++, for example, due to the strong typechecking
features. Also, C++ is not a pure object oriented programming
language due to the fact that it maintains compatibility with C,
where as Java is much more object oriented.

One more feature which deserves a special mention is operator
overloading. This is where an object is defined, and the
programmer can design how those objects behave when they
are combined with arithmetic operators such as +,-, and even
[]. The great thing about this is that the person using the object
can make intuitively sensible code - a brief example is the
string class. You are probably familiar strcat and strcpy, but using
operator overloading, "adding" one string to another acts like
strcat, and using the equals sign to assign the result to another
is like strcpy.

Well thats all i have for you, so to answer your question on cout
and cin, well they stand for console out and console in - they
are actually objects, and the syntax of writing to the screen
using cout using the binary shift operator << is actually an
implementation of the overloading i just spoke about, and
intuitively respresents "shifting" text into the object, resulting in
it being displayed on screen, or shifting a value in from the
console into your variable.

Man thats a long post, but i hope you find it interesting and
motivating, and detailed enough for you as well. Good luck
on entering the world of C++. I leave you with this link to the
man who designed C++ - Bjarne Stroustrup

http://public.research.att.com/~bs/C++.html

Originally Posted by Ancient Dragon

Yup -- I'm guilty of that

I'd like to say I'm guilty of that, but unfortunately, I write both C and C++ much more comparably to a smoldering pile of poo.

OO programming isn't restricted to any particular programming language. I know this C guy who uses a myriad of function pointers in structs to simulate member functions

OO is a concept. Even the converse is not true. You don't need OO to program in C++.

Originally Posted by tweeres04

Awesome, thanks for all of that, especially richie. A lot of help. Now at least I have some sort of idea of what needs to be learned. I'll also keep in mind that I should try to not program in C using classes.
Thanks again.

And forget everything you think you know about i/o.. dynamic memory.. strings... arrays... casting.. C++ Does it all quite differently... You're really starting a whole new language, all from scratch

C++ is actually a "multi-paradigm" language. There are bascially 3 seperate paradigms within C++:

• C: plain 'ol procedural programming
• Object Oriented: Classes, inheritance, polymorphism, encapsulation, etc
• <Generic> programming: templates, containers, the STL, boost and (omg teh n0es) template metaprogramming (if you don't know what this is, now is not the time to learn)

most beginners start with C and move to a mix of C and OO (c with classes). As they progress they move more to OO and eventually to a mix of OO and generic programming. Advanced programmers know when to use all 3 aspects.

Originally Posted by esbo

"multi-paradigm"
C++ is a language for salesmen.

ok I didn't respond to your first post 'cos I thought you were joking, but in the grown up world we sometimes use words longer than 5 letters. Yes, C++ is a "multi-paradigm" language, or in words you can understand, C++ allows you to do things in different ways.

Honestly, if you're going to post on a C++ board that "C++ is a waste of time and space", you should try to have something that resembles a rational arguement to back it up.

>> I have the 'inventors' book and found it pretty incomprehensible.
Your own stupidity does not make C++ a bad language.

>> C++ is to programming what bicycles are to fishes.
wow, what an insightful comment! I'm never going to write another line of C++ due to your intelligent, reasoned argument. Oh, hang on, there wasn't one.

C++ has its faults (many of which it inherited from C). It's not a perfect language and it's not suited to every task (these days I generally prefer Python for most programming tasks), but as a highly efficient real-world systems level language, nothing comes close.