What is C++

What is C++?

C and C++

Dennis Ritchie developed C and it was quite popular. An interesting feature in C is the use of functions. The programmer could write a function for checking whether a number is odd or even and store it in a separate file. In the program, whenever it is needed to check for even numbers, the programmer could simply call that function instead of rewriting the whole code. Usually a set of commonly used functions would be stored in a separate file and that file can be included in the current project by simply using the #include <filename> syntax. Thus the current program will be able to access all functions available in ‘filename’. Programs written in C were more structured compared to high level languages and another feature was the ability to create your own data types like structures. For instance if you want to create an address book program, you will need to store information like name and telephone number. The name is a string of characters while the telephone number is an integer number. Using structures you can combine both into one unit. Similarly there are many more advantages of C.

Though C seemed to be ideal, it was not effective when the programs became more complex (or very large). The use of many functions (developed by various users) led to a clash of variable names. Though C is much more efficient than BASIC, a new concept called Object Oriented Programming seemed better than C. OOP was the basis of C++ (which was initially called ‘C with classes’). C++ was developed by Bjarne Strastroup. In object oriented programming, the programmer can solve problems by breaking them down into real-life objects (it presented the programmer with an opportunity to mirror real life). What is an object? This topic is dealt with extensively in the chapter on ‘Objects and Classes’ but a brief introduction is provided here.

Consider the category of cars. All cars have some common features (for example all cars have four wheels, an engine, some body colour, seats etc.). Are all cars the same? Of course not. A Fiat and a Ford aren’t the same but they are called as cars in general. In this example cars will form a class and Ford (or Fiat) will be an object.

For those people who know C programming, it would be useful to know the differences between C and C++. Basically C++ includes everything present in C but the use of some C features is deprecated in C++.

C does not have classes and objects (C does not support OOP)
Structures in C cannot have functions.
C does not have namespaces (namespaces are used to avoid name collisions).
The I/O functions are entirely different in C and C++ (ex: printf( ), scanf( ) etc. are part of the C language).
You cannot overload a function in C (i.e. you cannot have 2 functions with the same name in C).
Better dynamic memory management operators are available in C++.
C does not have reference variables (in C++ reference variables are used in functions).
In C constants are defined as macros (in C++ we can make use of ‘const’ to declare a constant).
Inline functions are not available in C.

To just recap the evolution of programming: initially programs were written in terms of 1s and 0s (machine language). The drawback was that the process was very tedious and highly error-prone. Assembly language was developed to write programs easily (short abbreviations were used instead of 1s and 0s). To make it even simpler for programmers, high level languages were developed (instructions were more similar to regular English). As the complexity of programs increased, these languages were found to be inadequate (because they were unstructured). C was developed but even that was not capable of dealing with complex or larger programs. This led to the development of C++.

Why do you need to learn C++?

There are many people who ask the question, "why should I learn C++? What use is it in my field?" It is a well-known fact that computers are used in all areas today. Programming is useful wherever computers are used because it provides you the flexibility of creating a program that suits your requirements. Even research work can be simulated on your computer if you have programming knowledge. Construction and programming may appear to be miles apart but even a civil engineer could use C++ programming. Consider the case of constructing a physical structure (like a pillar) in which the civil engineer has to decide on the diameter of the rods and the number of rods to be used. There are 2 variables in this case:

The number of rods needed (let’s denote it as ‘n’) and
The diameter of each rod (let’s call it as ‘d’)

The civil engineer might have to make a decision like: "Is it cost-effective for me to have 10 rods of 5cm diameter or is it better to have 8 rods of 6cm diameter?" This is just one of the simple questions he may have in his mind. There are a few related questions: "What is the best combination of number of rods, their diameters and will that combination be able to handle the maximum stress?"

Usually equations are developed for each of the factors involved. It would be much easier if the civil engineer could simply run a program and find out what is the best combination instead of manually trying out random values and arriving at a solution. This is where programming knowledge would benefit the engineer. Any person can write a good program if he has adequate knowledge about the domain (domain refers to the area for which the software is developed. In this case it is construction). Since the civil engineer has the best domain knowledge he would be able to write a program to suit his requirements if he knew programming.

Programming is applicable to almost every field- banking (for maintaining all account details as well as the transactions), educational institutions (for maintaining a database of the students), supermarkets (used for billing), libraries (to locate and search for books), medicine, electrical engineering (programs have been developed for simulating circuits) etc.

A class defines what data is used to represent an object and the operations that can be performed on the data.

Object Oriented Programming (C++)

Emphasis on the data rather than the problem

Uses classes and objects to represent data.

Bottom-Up Design (move from objects to classes to program design)

Data hiding - Protect the data (by using private feature of classes).
Polymorphism - create many definitions for the same operators.
Inheritance - derive new classes from existing ones.

Enough on the theory. You'll understand better once you start learning C++. Objects and classes may seem a weird idea but don't worry. We'll deal with it later on.

Go on to the next section on : Terms used in C++

Or go back to the : Contents.