Computer Programming

It is understood that programming languages are used to create programs and a program is a sequence of instructions written to perform a specified task with a computer.The important thing to be noted is - there are different tasks and different types of tasks that are to be performed with a computer and thus the facilities offered by a single programming language is not enough to accomplish all those tasks.

In other words the features or purpose of one programming language differs from others (for example HTML is used to create websites and C or Shell programming can be used for system programming). Different programming languages are also used in different platforms to perform the same task (for example Visual C# or Visual C++ can be used for creating an application in Windows but Objective C is used to create the same application in Mac OS X).So different programming language are used to create program to perform different types of tasks due to limitations in the facilities offered by a single programming language.

Regardless of what programming language has been used, the particular compiler for that programming language compiles the program and creates its equivalent executable code(.exe file) in machine language(0 and 1), which the computer understands.

the list is as follows with the description :-

; Class : Defines the abstract characteristics of a thing (object), including the thing's characteristics (its attributes, fields or properties) and the thing's behaviors (the things it can do, or methods, operations or features). One might say that a class is a blueprint or factory that describes the nature of something. For example, the class Dog would consist of traits shared by all dogs, such as breed and fur color (characteristics), and the ability to bark and sit (behaviors). Classes provide modularity and structure in an object-oriented computer program. A class should typically be recognizable to a non-programmer familiar with the problem domain, meaning that the characteristics of the class should make sense in context. Also, the code for a class should be relatively self-contained (generally using encapsulation). Collectively, the properties and methods defined by a class are called members. ; Object : A pattern (exemplar) of a class. The class of Dog defines all possible dogs by listing the characteristics and behaviors they can have; the object Lassie is one particular dog, with particular versions of the characteristics. A Dog has fur; Lassie has brown-and-white fur. ; Instance : One can have an instance of a class or a particular object. The instance is the actual object created at runtime. In programmer jargon, the Lassie object is an instance of the Dog class. The set of values of the attributes of a particular object is called its state. The object consists of state and the behaviour that's defined in the object's class. ; Method : An object's abilities. In language, methods (sometimes referred to as "functions") are verbs. Lassie, being a Dog, has the ability to bark. So bark() is one of Lassie's methods. She may have other methods as well, for example sit() or eat() or walk() or save_timmy(). Within the program, using a method usually affects only one particular object; all Dogs can bark, but you need only one particular dog to do the barking. ; Message passing : "The process by which an object sends data to another object or asks the other object to invoke a method." [2] Also known to some programming languages as interfacing. For example, the object called Breeder may tell the Lassie object to sit by passing a "sit" message which invokes Lassie's "sit" method. The syntax varies between languages, for example: [Lassie sit] in Objective-C. In Java, code-level message passing corresponds to "method calling". Some dynamic languages use double-dispatch or multi-dispatch to find and pass messages. ; Inheritance : "Subclasses" are more specialized versions of a class, which inherit attributes and behaviors from their parent classes, and can introduce their own. : For example, the class Dog might have sub-classes called Collie, Chihuahua, and GoldenRetriever. In this case, Lassie would be an instance of the Collie subclass. Suppose the Dog class defines a method called bark() and a property called furColor. Each of its sub-classes (Collie, Chihuahua, and GoldenRetriever) will inherit these members, meaning that the programmer only needs to write the code for them once. : Each subclass can alter its inherited traits. For example, the Collie class might specify that the default furColor for a collie is brown-and-white. The Chihuahua subclass might specify that the bark() method produces a high pitch by default. Subclasses can also add new members. The Chihuahua subclass could add a method called tremble(). So an individual chihuahua instance would use a high-pitched bark() from the Chihuahua subclass, which in turn inherited the usual bark() from Dog. The chihuahua object would also have the tremble() method, but Lassie would not, because she is a Collie, not a Chihuahua. In fact, inheritance is an "a... is a" relationship between classes, while instantiation is an "is a" relationship between an object and a class: a Collie is a Dog ("a... is a"), but Lassie is a Collie ("is a"). Thus, the object named Lassie has the methods from both classes Collie and Dog. : Multiple inheritance is inheritance from more than one ancestor class, neither of these ancestors being an ancestor of the other. For example, independent classes could define Dogs and Cats, and a Chimera object could be created from these two which inherits all the (multiple) behavior of cats and dogs. This is not always supported, as it can be hard both to implement and to use well. ; Abstraction : Abstraction is simplifying complex reality by modelling classes appropriate to the problem, and working at the most appropriate level of inheritance for a given aspect of the problem. : For example, Lassie the Dog may be treated as a Dog much of the time, a Collie when necessary to access Collie-specific attributes or behaviors, and as an Animal (perhaps the parent class of Dog) when counting Timmy's pets.

Abstraction is also achieved through Composition. For example, a class Car would be made up of an Engine, Gearbox, Steering objects, and many more components. To build the Car class, one does not need to know how the different components work internally, but only how to interface with them, i.e., send messages to them, receive messages from them, and perhaps make the different objects composing the class interact with each other. ; Encapsulation : Encapsulation conceals the functional details of a class from objects that send messages to it. : For example, the Dog class has a bark() method. The code for the bark() method defines exactly how a bark happens (e.g., by inhale() and then exhale(), at a particular pitch and volume). Timmy, Lassie's friend, however, does not need to know exactly how she barks. Encapsulation is achieved by specifying which classes may use the members of an object. The result is that each object exposes to any class a certain interface - those members accessible to that class. The reason for encapsulation is to prevent clients of an interface from depending on those parts of the implementation that are likely to change in future, thereby allowing those changes to be made more easily, that is, without changes to clients. For example, an interface can ensure that puppies can only be added to an object of the class Dog by code in that class. Members are often specified as public, protected or private, determining whether they are available to all classes, sub-classes or only the defining class. Some languages go further: Java uses the default access modifier to restrict access also to classes in the same package, C# and VB.NET reserve some members to classes in the same assembly using keywords internal (C#) or Friend (VB.NET), and Eiffel and C++ allow one to specify which classes may access any member. ; Polymorphism : Polymorphism allows the programmer to treat derived class members just like their parent class' members. More precisely, Polymorphism in object-oriented programming is the ability of objects belonging to different data types to respond to method calls of methods of the same name, each one according to an appropriate type-specific behavior. One method, or an operator such as +, -, or *, can be abstractly applied in many different situations. If a Dog is commanded to speak(), this may elicit a bark(). However, if a Pig is commanded to speak(), this may elicit an oink(). They both inherit speak() from Animal, but their derived class methods override the methods of the parent class; this is Overriding Polymorphism. Overloading Polymorphism is the use of one method signature, or one operator such as "+", to perform several different functions depending on the implementation. The "+" operator, for example, may be used to perform integer addition, float addition, list concatenation, or string concatenation. Any two subclasses of Number, such as Integer and Double, are expected to add together properly in an OOP language. The language must therefore overload the addition operator, "+", to work this way. This helps improve code readability. How this is implemented varies from language to language, but most OOP languages support at least some level of overloading polymorphism. Many OOP languages also support Parametric Polymorphism, where code is written without mention of any specific type and thus can be used transparently with any number of new types. Pointers are an example of a simple polymorphic routine that can be used with many different types of objects.[3] ; Decoupling : Decoupling allows for the separation of object interactions from classes and inheritance into distinct layers of abstraction. A common use of decoupling is to polymorphically decouple the encapsulation, which is the practice of using reusable code to prevent discrete code modules from interacting with each other. However, in practice decoupling often involves trade-offs with regard to which patterns of change to favor. The science of measuring these trade-offs in respect to actual change in an objective way is still in its infancy. Not all of the above concepts are to be found in all object-oriented programming languages, and so object-oriented programming that uses classes is called sometimes class-based programming. In particular, prototype-based programming does not typically use classes. As a result, a significantly different yet analogous terminology is used to define the concepts of object and instance.

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1. ABC
2. Ada
3. Algol 60
4. Algol 68
5. APL
6. Arc
7. Assembly
8. Awk
9. BASIC
10. Batch
11. BCPL
12. Befunge
13. BETA
14. C
15. C++
16. C--
17. C# (pronounced C-sharp)
18. CHILL
19. Clipper
20. Cobol
21. CobolScript
22. Component Pascal
23. Cyclone
24. D
25. DATABUS
26. Euphoria
27. Forth
28. Fortran
29. Free Pascal
30. GNU Pascal
31. Icon
32. IDL
33. Jal
34. JavaScript
35. Jovial
36. Lagoona
37. Leda
38. Limbo
39. Lua
40. m4
41. Maple
42. Mathematica
43. MATLAB
44. Modula-2
45. Modula-3
46. Mumps
47. Oberon
48. Objective Caml (OCaml)
49. Occam
50. Oz-Mozart
51. Pascal
52. Perl
53. PHP
54. PL
55. PL/1
56. Pliant
57. PL/SQL
58. PostScript
59. PowerBuilder
60. Proteus
61. REBOL
62. Rexx
63. S-Lang
64. Small C
65. Snobol
66. Tcl-Tk
67. T3X
68. VBA
69. Visual Basic
70. Visual DialogScript
71. Yorick

Note: Some of these languages, such as PHP, Perl, Caml/OCaml, and IDL also support object oriented programming. Others on the list (C++, JavaScript, C# ) are primarily object-oriented languages which can also (though less commonly) be used to program procedurally.

Some are macro or scripting languages (Rexx, Awk, m4) which, while they do support some procedural concepts, aren't really procedural languages, but rather interpreted streams.

Also note that Assembly is NOT a high-level language, and generally is not considered a procedural language, as it doesn't have enough abstraction.

Finally, traditional COBOL is NOT a procedural language (in fact, one of the long-standing criticism of it is that it lacks any structured programming characteristics). Current-day COBOL has some ability to use procedural programming concepts, but, overall, should not be considered a real procedural language. SNOBOL is similar, in that the original version were certainly not procedural in nature, but modern versions are much more structured programming friendly (and can be considered a procedural language).

Imperative languages, also called algorithmic languages, are probably

the most prevalent among the programming language paradigms today.

Their programs are constructed as algorithms or as sequences of

executable instructions.

These languages are greatly concerned with variables and include

commands for sequentially allocating memory space or CPU locations to

these variables and for correspondingly changing their values through

assignment statements or procedure execution.

The three main categories of imperative languages are as follows:

· Block-Structured or Procedural Languages - These languages are

process or "how" oriented. Their basic unit of modularization is the

function or the procedure. A modular unit is comprised of a set of

data declarations and statements. Examples: ALGOL, Pascal,

Modula-2, Ada, and C.

· Object-Oriented Languages - These languages are data or "what"

centered and implement the principle of program decomposition,

data abstraction, and information hiding. They are based on the

fundamental concept of objects. Examples: Smalltalk, C++, Java,

and Visual Basic.

· Distributed Programming Languages - These languages support

more than one processor working either simultaneously or

alternately with other processors in order to complete a task or to

solve a problem.

Declarative languages are those based on relations or functions. Theyinclude facilities for writing declarations or truths. Compared to

imperative languages, they are considered to have higher level than the

former since they work around concepts and not with a machine's

storage locations.

The three main categories of declarative languages are as follows:

· Functional or Applicative Languages - These languages consider

the function as their major organizing principle. Examples: LISP,

APL, and ML.

· Logic Programming - These languages describe computing

problems in the form of predicate logic statements. PROLOG is the

first thing that comes to mind when talking about logic programming.

· Languages for Databases - Languages that support databases

include facilities for accessing/selecting data from database entities,

and describing relationships between data entities. Example: SQL.

Weak typing is where a language allows you to treat blocks of memory defined as one type as another (casting). Languages like C and C++, although statically typed, are weakly typed.

Languages like Perl and PHP are weakly typed because you can do things like adding numbers to strings and the language will do an implicit coercion for you.

Languages like Java, C# and Python are strongly typed - there is no way you can add a number to a string without doing an explicit conversion.

In addition, there are many large systems that have been created with dynamic type systems. Catching type errors (typos) at compile time only catches a very small proportion of errors and a strong testing strategy produces much more reliable systems irrespective of the type system in use.

Strong type is checking the types of variables at compile time. weak typing is checking the types of the system at run-time. For scripts & quick stuff we'll use weak typing, In big programs, strong typing can reduce errors at compile time

The above answer is not 100% correct. C++ doesn't allow for an integer (int) to be added to a string, unless you mean appending. In which case, C# and Java behave in similar fashion by doing an implicit conversion. For a better answer see the answer to "Strongly typed programming language" in this site.

Juan R

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Strong typing provides greater type safety. You might have specially heard it about DataSets being strongly typed, where instead of referring columns as datacolumns(index).value, you create an XML schema from which you make a dataset derived class. Strong typing is preferred as there remains no type ambiguity. Another example is, turning on Option strict in VB, where you have to do explicit type casts.Instead of running into situation where you get a type that you did not expect and try performing an operation on it, you go for strong typing so that such errors are caught during compile time itself.

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strong typelanguage specication requires its typing rules strongly (i.e. more or less allowing only those automatic type conversions which do not lose information),

one can refer to the process as strongly typed, if not, as weakly typed.

example in c language

int a;

float b, c;

b=2.2;

c=3.3;

a=b+c;// here we are losing data result is 5 instead of 5.5 because a is an integer

cout<

here ouptput 5.

if language do not allow to automatic type conversion then it should be strongly type otherwise it is weakly typed.

dynamic type:- if compiler know information about the type of variable or data at run time then it is called dynamic type.

static type:- if complier get information about type of variable or data at compile time then it is called static type.