Introduction to Programming Languages

What is a Programming Language?

 A programming language is a formal computer language or constructed language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs to control the behavior of a machine.

Types of programming Languages

1. Low level Language
2. High level language

1. Low level language

• Low-level language is a programming language that deals with a computer's hardware components
• Low-level languages are designed to operate and handle the entire hardware and instructions set architecture of a computer directly.

There are two types of low level languages

1. Machine language
2. Assembly Language

1. Machine Language -->Machine code or machine language is a set of instructions executed directly by a computer's central processing unit (CPU). Each instruction performs a very specific task, such as a load, a jump, or an ALU operation on a unit of data in a CPU register or memory. Every program directly executed by a CPU is made up of a series of such instructions.

2. Assembly languages

           -An assembly language is a low-level programming language for microprocessors and other                    programmable devices.

           -Assembly language implements a symbolic representation of the machine code needed to                      program a given CPU architecture.

           -Assembly language is a mathematical and logical symbol that used to communicate to the                   computer.

1. High level language

High-level language is a computer programming language that is designed for a specific job, and is easier to understand. Its source code is written in human understandable language. However, for a computer to understand and run a program created with a high-level language, it must be compiled into machine language.

Ex: FORTRAN, ALGO, LISP, COBOL, C, C++, JAVA

FORTRAN-->The first important algorithmic language was FORTRAN (formula translation), designed in 1957 by an IBM team led by John Backus. It was intended for scientific computations with real numbers and collections of them organized as one- or multidimensional arrays. Its control structures included conditional IF statements, repetitive loops (so-called DO loops), and a GOTO statement that allowed non sequential execution of program code.

ALGOL-->ALGOL (algorithmic language) was designed by a committee of American and European computer scientists during 1958–60 for publishing algorithms, as well as for doing computations. Like LISP (described in the next section), ALGOL had recursive subprograms—procedures that could invoke themselves to solve a problem by reducing it to a smaller problem of the same kind. ALGOL introduced block structure, in which a program is composed of blocks that might contain both data and instructions and have the same structure as an entire program. Block structure became a powerful tool for building large programs out of small components.

 LISP-->LISP (list processing) was developed about 1960 by John McCarthy at the Massachusetts Institute of Technology (MIT) and was founded on the mathematical theory of recursive functions (in which a function appears in its own definition). A LISP program is a function applied to data, rather than being a sequence of procedural steps as in FORTRAN and ALGOL. LISP uses a very simple notation in which operations and their operands are given in a parenthesized list. LISP became a common language for artificial intelligence (AI) programming, partly owing to the confluence of LISP and AI work at MIT and partly because AI programs capable of “learning” could be written in LISP as self-modifying programs.

C Language--->The C programming language was developed in 1972 by Dennis Ritchie and Brian Kernighan at the AT&T Corporation for programming computer operating systems. Its capacity to structure data and programs through the composition of smaller units is comparable to that of ALGOL. It uses a compact notation and provides the programmer with the ability to operate with the addresses of data as well as with their values. This ability is important in systems programming, and C shares with assembly language the power to exploit all the features of a computer’s internal architecture.

Business-oriented languages

COBOL-->COBOL (common business oriented language) has been heavily used by businesses since its inception in 1959.COBOL uses an English-like notation—novel when introduced. Business computations organize and manipulate large quantities of data, and COBOL introduced the record data structure for such tasks. A record clusters heterogeneous data such as a name, ID number, age, and address into a single unit. This contrasts with scientific languages, in which homogeneous arrays of numbers are common. Records are an important example of “chunking” data into a single object, and they appear in nearly all modern languages.

What is Structure Procedure Programming?

- In the early time the Structure Procedure programming was widely used designing and developing software.

-Structure procedure programming is a programming paradigm (pattern of something) or a technique for design and development of software in which the complex program is divided into small unit called function or subroutines also called procedure so that the complexity of program can be reduce and the code can be reuse. But later this approach was found unsuitable for more complex software. Because the function and variable was stored separately and there is no technique to hiding data.

- In this technique the softer maintenance was complex and security was weak. It was not suitable for more complex software. So a new approach come called object oriented programming.

What is Object oriented Programming?

- Object oriented programming is an approach or technique design and development of software based on the following idea

- Encapsulation, abstraction, inheritance, data hiding, polymorphism.

- In object oriented programming the object is the basic unit of object oriented programming. Designing the object oriented model involving defining set of classes. A class is a template from which object are created.

- In object oriented programming the object state (data) and behavior (function) are encapsulate within in class. The message passing ensures that it can be accessible if it is permitted. It prevents unauthorized access. Evaluation of OOP

- The OOP (Object Oriented Programming) approach is most commonly used approach now a day. OOP is being used for designing large and complex applications. Before OOP many programming approaches existed which had many drawbacks.

- These programming approaches have been passing through revolutionary phases just like computer hardware. Initially for designing small and simple programs, the machine language was used. Next come the Assembly Language which was used for designing larger programs. Both machine and Assembly languages is machine dependent. Next come Procedural Programming Approach which enabled us to write larger and hundred lines of code. Then in 1970, a new programming approach called Structured Programming Approach was developed for designing medium sized programs. In 1980's the size of programs kept increasing so a new approach known as OOP was invented.

Note: Programming paradigms are a way to classify programming languages according to the style of computer programming.

Object oriented Paradigm

-Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which may contain data, in the form of fields, often known as attributes; and code, in the form of procedures, often known as methods. A feature of objects is that an object's procedures can access and often modify the data fields of the object with which they are associated (objects have a notion of "this" or "self"). In OOP, computer programs are designed by making them out of objects that interact with one another.

- OOP is a better way of solving computer problems compared to a procedural programming language such as C. OOP uses classes which contain members (variables) and methods (functions). OOP uses a modular type of programming structure.

- OOP is a type of programming in which programmers define not only the data type of a data structure, but also the types of operations that can be applied to the data structure. In this way, the data structure becomes an object that includes both data and functions. In addition, programmers can create relationships between one object and another. For example, objects can inherit characteristics from other objects.

- One of the main advantages of object-oriented programming over procedural programming is that they enable programmers to create modules that do not need to be changed when a new type of object is added. A programmer can simply create a new object that inherits many of its features for existing objects. This makes object-oriented programs easier to modify.

Advantage of oop

The main advantage or merits or benefit are given below

- Oop provide better syntax structure, modeling real world is easy and flexible.

- Complex software system can be modularize on the basic of class and object

- Creation and maintenance is easy hence reduce software development time.

- Data encapsulation and data hiding increase software reliability and modifiability.

- Polymorphism and dynamic binding increase flexibility of code.

- Inheritance allows software code to extensible and reuse

Disadvantage of oop

The main disadvantage or demerits or drawback are given below

- Oop decompose large hierarchy of classes is complex and difficulty toi maintain

- Polymorphism and dynamic binding also required long processing, due to the overhead of function calls during the runtime.

- Oop software and debugging and testing tools are not standardized.

- For small application oop is not suite.

Comparison of structure procedural programming (SPP) and OOP