There are some techniques in C++ which are referred to as template tricks or some people I know call them esoteric. But these are no tricks. Mainly it is the compiler that is clever enough to find out a lot of things about the code written by the programmer. When programming with templates the programmer doesn't refer to a certain type, normally. The function or class is template is written in a way that a great number of types can be specified to fill the gap and act as arguments. When the programmer writes such templates he or she doesn't refer to the type itself but to properties that a type must fulfill to be usable with the template. The thing that makes this possible is called parametric polymorphism. The operations invoked on the template parameter have to defined for that (user defined) type argument. Thus the type argument is usable in a certain way, for instance an object of the type used as template argument can be copied or it can be assigned or it can be called (it is a callable entity). The type has to model a specific concept.

You might think: "What is this useful for?". And you're right. The answer is: It helps you you to abstract (still on a language level) in a much better way. You can write algorithm templates for certain parts of your program and provide (sometimes with the help of some glue code) varying parts of these algorithm. And since these parts are usable with the same syntax, you have achieved another important victory. You found out what parameters are necessary for the varying parts, for instance compare calling a function object with calling a function - nothing is different (provided the return types and the parameter lists are identical). This is great because it enables reuse in a much better way. It is more efficient because all the hard work of finding out whether a template argument can be used correctly is done during compile time and not during runtime. It enables you to write a better code because this technique can be used to prevent you from repeating certain parts of the program again and again. Finally coding this way makes you a better programmer because you are encouraged to generalize in an appropriate way. You have to be concise (in what you require from template arguments) and on the other hand you don't need to deal with unnecessarily detailed code. Thus the concepts of the software are represented in a better way. I am constantly improving these skills for myself.

Answered by M P , an ibibo Master, at 6:18 PM on October 06, 2008

well,
Polymorphism is a generic term that means 'many shapes'. In C++ the simplest form of Polymorphism is overloading of functions, for instance several functions called SortArray( arraytype ) where sortarray might be an array of ints, or doubles.

We're only interested here though in the OOP form of polymorphism. This is done by making a function (e.g. Draw() ) virtual in the base class Point and then overriding it in the derived class Circle.

Although the function Draw() is virtual in the derived class Circle, this isn't actually needed- it's a reminder to me that this it is virtual. If the function in a derived class matches a virtual function in the base class on name and parameter types, it is automatically virtual.
source site: http://cplus.about.com/od/lear ning1/ss/cppobjects_7.htm

Answered by Nidhi Singh , an ibibo Master, at 11:13 AM on September 24, 2008

A form of genetic variation, specifically a discontinuous variation, occurring within plant and animal species in which distinct forms exist together in the same population, even the rarest of them being too common to be maintained solely by mutation. Thus the human blood groups are examples of polymorphism, while geographical races are not; nor is the diversity of height among humans, because height is “continuous” and does not fall into distinct tall, medium, and short types. See also Mutation.

Distinct forms must be controlled by some switch which can produce one form or the other without intermediates such as those arising from environmental differences. This clear-cut control is provided by the recombination of the genes. Each gene may have numerous effects and, in consequence, all genes are nearly always of importance to the organism by possessing an overall advantage or disadvantage. They are very seldom of neutral survival value, as minor individual variations in appearance often are. Thus a minute extra spot on the hindwings of a tiger moth is in itself unlikely to be of importance to the survival of the insect, but the gene controlling this spot is far from negligible since it also affects fertility. See also Recombination (genetics).

Genes having considerable and discontinuous effects tend to be eliminated if harmful, and each gene of this kind is therefore rare. On the other hand, those that are advantageous and retain their advantage spread through the population so that the population becomes uniform with respect to these genes. Evidently, neither of these types of genes can provide the switch mechanism necessary to maintain a polymorphism. That can be achieved only by a gene which has an advantage when rare, yet loses that advantage as it becomes commoner.

Occasionally there is an environmental need for diversity within a species, as in butterfly mimicry. Mimicry is the resemblance of different species to one another for protective purposes, chiefly to avoid predation by birds. Sexual dimorphism falls within the definition of genetic polymorphism. In any species, males and females are balanced at optimum proportions which are generally near equality. Any tendency for one sex to increase relative to the other would be opposed by selection.

In general, a gene having both advantageous and disadvantageous effects may gain some overall advantage and begin to spread because one of the features it controls becomes useful in a new environment. A balance is then struck between the advantages and disadvantages of such a gene, ensuring that a proportion of the species carry it, thus giving rise to permanent discontinuous variation, that is, to polymorphism. See also Protective coloration.

Polymorphism is increasingly known to be a very common situation. Its existence is apparent whenever a single gene having a distinct recognizable effect occurs in a population too frequently to be due merely to mutation. Even if recognized by some trivial effect on the phenotype, it must in addition have important other effects. About 30% of the people in western Europe cannot taste as bitter the substance phenylthiourea. This is truly an insignificant matter; indeed, no one even had the opportunity of tasting it until the twentieth century. Yet this variation is important since it is already known that it can affect disease of the thyroid gland. See also Genetics; Population genetics.

Source:

http:/ /www.answers.com/topic/polymor phism

Answered by Sharad Singh , an ibibo Master, at 6:28 PM on September 18, 2008

Polymorphism is another important feature of Object Oriented Programming.Polymorphism means one function existing in many forms.There will be many functions of the same name and only the number of parameters, type of parameters, and the order in which they appear will be different.

1. Important feature of Object Oriented Programming
2. Polymorphism - One function and many forms
3. Number of parameters, type of parameters, order in which they appear differs
4. Compiler binds call to function at compilation time itself - static polymorphism
5. Compiler binds call to the function at runtime depending upon context - Dynamic polymorphism

Polymorphism is the ability of an object to exist in different forms. In Object Oriented Programming, it is the ability of a function to behave differently, depending on the context in which it is called.

Answered by Ashish Yadav , an ibibo Wizard, at 4:03 PM on September 11, 2008

"Poly" means "many" and "morph" means "form". Polymorphism is the ability of an object (or reference) to assume (be replaced by) or become many different forms of object.
Example: function overloading, function overriding, virtual functions.
Another example can be a plus ‘+’ sign, used for adding two integers or for using it to concatenate two strings.

In programming languages, polymorphism means that some code or operations or objects behave differently in different contexts.

For example, the + (plus) operator in C++:

4 + 5 <-- integer addition
3.14 + 2.0 <-- floating point addition
s1 + "bar" <-- string concatenation!

In C++, that type of polymorphism is called overloading.

Typically, when the term polymorphism is used with C++, however, it refers to using virtual methods.

Answered by NEVIDITA , an ibibo Master, at 2:15 PM on September 08, 2008

well;
Polymorphism is the ability to use an operator or function in different ways. Polymorphism gives different meanings or functions to the operators or functions. Poly, referring to many, signifies the many uses of these operators and functions. A single function usage or an operator functioning in many ways can be called polymorphism. Polymorphism refers to codes, operations or objects that behave differently in different contexts.

Below is a simple example of the above concept of polymorphism:


6 + 10

The above refers to integer addition.

The same + operator can be used with different meanings with strings:


"Exforsys" + "Training"

The same + operator can also be used for floating point addition:


7.15 + 3.78

Polymorphism is a powerful feature of the object oriented programming language C++. A single operator + behaves differently in different contexts such as integer, float or strings referring the concept of polymorphism. The above concept leads to operator overloading. The concept of overloading is also a branch of polymorphism. When the exiting operator or function operates on new data type it is overloaded. This feature of polymorphism leads to the concept of virtual methods.

Polymorphism refers to the ability to call different functions by using only one type of function call. Suppose a programmer wants to code vehicles of different shapes such as circles, squares, rectangles, etc. One way to define each of these classes is to have a member function for each that makes vehicles of each shape. Another convenient approach the programmer can take is to define a base class named Shape and then create an instance of that class. The programmer can have array that hold pointers to all different objects of the vehicle followed by a simple loop structure to make the vehicle, as per the shape desired, by inserting pointers into the defined array. This approach leads to different functions executed by the same function call. Polymorphism is used to give different meanings to the same concept. This is the basis for Virtual function implementation.

In polymorphism, a single function or an operator functioning in many ways depends upon the usage to function properly. In order for this to occur, the following conditions must apply:

* All different classes must be derived from a single base class. In the above example, the shapes of vehicles (circle, triangle, rectangle) are from the single base class called Shape.
* The member function must be declared virtual in the base class. In the above example, the member function for making the vehicle should be made as virtual to the base class.

Answered by Kishore , an ibibo Master, at 8:16 AM on September 08, 2008

Polymorphism is the ability to use an operator or function in different ways. Polymorphism gives different meanings or functions to the operators or functions. Poly, referring to many, signifies the many uses of these operators and functions. A single function usage or an operator functioning in many ways can be called polymorphism. Polymorphism refers to codes, operations or objects that behave differently in different contexts.

Below is a simple example of the above concept of polymorphism:
6 + 10
The above refers to integer addition.

Polymorphism is a powerful feature of the object oriented programming language C++. A single operator + behaves differently in different contexts such as integer, float or strings referring the concept of polymorphism. The above concept leads to operator overloading. The concept of overloading is also a branch of polymorphism. When the exiting operator or function operates on new data type it is overloaded. This feature of polymorphism leads to the concept of virtual methods.

Polymorphism refers to the ability to call different functions by using only one type of function call. Suppose a programmer wants to code vehicles of different shapes such as circles, squares, rectangles, etc. One way to define each of these classes is to have a member function for each that makes vehicles of each shape. Another convenient approach the programmer can take is to define a base class named Shape and then create an instance of that class. The programmer can have array that hold pointers to all different objects of the vehicle followed by a simple loop structure to make the vehicle, as per the shape desired, by inserting pointers into the defined array. This approach leads to different functions executed by the same function call. Polymorphism is used to give different meanings to the same concept. This is the basis for Virtual function implementation.

In polymorphism, a single function or an operator functioning in many ways depends upon the usage to function properly. In order for this to occur, the following conditions must apply:

* All different classes must be derived from a single base class. In the above example, the shapes of vehicles (circle, triangle, rectangle) are from the single base class called Shape.
* The member function must be declared virtual in the base class. In the above example, the member function for making the vehicle should be made as virtual to the base class.

Features and Advantages of the concept of Polymorphism:
Applications are Easily Extendable:

Once an application is written using the concept of polymorphism, it can easily be extended, providing new objects that conform to the original interface. It is unnecessary to recompile original programs by adding new types. Only re-linking is necessary to exhibit the new changes along with the old application. This is the greatest achievement of C++ object-oriented programming. In programming language, there has always been a need for adding and customizing. By utilizing the concept of polymorphism, time and work effort is reduced in addition to making future maintenance easier.

* Helps in reusability of code.
* Provides easier maintenance of applications.
* Helps in achieving robustness in applications.

Types of Polymorphism:

C++ provides three different types of polymorphism.

* Virtual functions
* Function name overloading
* Operator overloading

In addition to the above three types of polymorphism, there exist other kinds of polymorphism:

* run-time
* compile-time
* ad-hoc polymorphism
* parametric polymorphism

Other types of polymorphism defined:
run-time:

The run-time polymorphism is implemented with inheritance and virtual functions.

compile-time:

The compile-time polymorphism is implemented with templates.

Answered by jaivir , an ibibo Master, at 6:07 PM on September 07, 2008