### Practical Example of Using Virtual Functions II

From the past few articles we have been discussing about Virtual Functions. Before taking up another topic for discussion I thought of providing one more example of how and when virtual functions may be used. So, here it is, a practical example of virtual function.

As virtual functions and Run-Time Polymorphism goes hand-in-hand so the example here may also serve as an example of the use of run-time polymorphism.

``````
// Example to illustrate
// the use of virtual functions
// and run-time polymorphism
#include <iostream.h>

// -- SORT CLASS --
class sort
{
protected:
int *arr;
int num_elmnt;

public:
sort(int);
~sort();
void get_elmnt();
void show_elmnt();
virtual void do_sorting()=0;
};

// takes an argument
// which is the number of
// elements we want
sort::sort(int x)
{
num_elmnt=x;
arr=new int[num_elmnt];
}

sort::~sort()
{
// free up he allocated memory
delete []arr;
}

void sort::get_elmnt()
{
// input elements
cout<<"\nEnter Elements...";
for(int i=0;i<num_elmnt;i++)
{
cout<<"\n#"<<i+1<<":";
cin>>arr[i];
}
}

void sort::show_elmnt()
{
// display the elements
cout<<"\nElements are...";
for(int i=0;i<num_elmnt;i++)
{
cout<<"\n#"<<i+1<<":";
cout<<arr[i];
}
}
// -- SORT CLASS ENDS --

// -- BUBBLE SORT CLASS --
class bubble_sort : public sort
{
public:
// constructor only calls the
// base constructor with the
// parameter
bubble_sort(int x):sort(x){}

void do_sorting();
};

void bubble_sort::do_sorting()
{
int temp;

// do bubble sorting
for(int i=0;i<num_elmnt;i++)
for(int j=0; j<(num_elmnt-1); j++)
if (arr[j]>arr[j+1])
{
temp=arr[j];
arr[j]=arr[j+1];
arr[j+1]=temp;
}
}
// -- BUBBLE SORT CLASS ENDS --

// -- SELECTION SORT CLASS --
class selctn_sort : public sort
{
public:
// just call the base class
// constructor
selctn_sort(int x):sort(x){}
void do_sorting();
};

void selctn_sort::do_sorting()
{
int temp;

// do selection sorting
for(int i=0;i<(num_elmnt-1);i++)
for(int j=i+1;j<num_elmnt;j++)
{
if(arr[i]>arr[j])
{
temp=arr[i];
arr[i]=arr[j];
arr[j]=temp;
}
}
};
// -- SELECTION SORT CLASS ENDS --

void main()
{
bubble_sort bubble(3);
selctn_sort selctn(5);
sort *ptr;

ptr=&bubble;
ptr->get_elmnt();
ptr->do_sorting();

ptr=&selctn;
ptr->get_elmnt();
ptr->do_sorting();

// again point to bubble
ptr=&bubble;
ptr->show_elmnt();

// again point to selctn
ptr=&selctn;
ptr->show_elmnt();
}

``````

Related Articles:

### Fix For Toshiba Satellite "RTC Battery is Low" Error (with Pictures)

RTC Battery is Low Error on a Toshiba Satellite laptop "RTC Battery is Low..." An error message flashing while you try to boot your laptop is enough to panic many people. But worry not! "RTC Battery" stands for Real-Time Clock battery which almost all laptops and PCs have on their motherboard to power the clock and sometimes to also keep the CMOS settings from getting erased while the system is switched off.  It is not uncommon for these batteries to last for years before requiring a replacement as the clock consumes very less power. And contrary to what some people tell you - they are not rechargeable or getting charged while your computer or laptop is running. In this article, we'll learn everything about RTC batteries and how to fix the error on your Toshiba Satellite laptop. What is an RTC Battery? RTC or CMOS batteries are small coin-shaped lithium batteries with a 3-volts output. Most laptops use

### The Best Way(s) to Comment out PHP/HTML Code

PHP supports various styles of comments. Please check the following example: <?php // Single line comment code (); # Single line Comment code2 (); /* Multi Line comment code(); The code inside doesn't run */ // /* This doesn NOT start a multi-line comment block /* Multi line comment block The following line still ends the multi-line comment block //*/ The " # " comment style, though, is rarely used. Do note, in the example, that anything (even a multi-block comment /* ) after a " // " or " # " is a comment, and /* */ around any single-line comment overrides it. This information will come in handy when we learn about some neat tricks next. Comment out PHP Code Blocks Check the following code <?php //* Toggle line if ( 1 ) {      // } else {      // } //*/ //* Toggle line if ( 2 ) {      // } else {      // } //*/ Now see how easy it is to toggle a part of PHP code by just removing or adding a single " / " from th

### Generating XML Feeds (RSS, Atom) Using PHP

RSS/ATOM feeds are very common these days and almost all Content Management Systems (CMS) can generate it. But in the case when you want to generate it yourself or just want to learn how you can, read on! Both RSS and ATOM feeds are written in eXtensible Markup Language (XML) standard markup. Not just standard markups, you also need to be sure of what and how you put data in those markup elements (tags). For all this refer to the feed specifications of RSS and ATOM . XML itself is very strict and the standard specifications makes it even harder to generate valid feeds. And moreover, why re-invent the wheel when we can have it – ready-made. The solution I'm referring to here is, to use a third-party Library – Universal FeedWriter. FeedWriter is a PHP class written by Anis uddin Ahmad that can dramatically  ease-off feeds (both RSS and Atom) generation. You can download this library from  here . Every feed should have at least the following data: Feed title URL(of the webs