C++ Programming

A pure-virtual method may provide an implementation, but it is not a requirement. If you find that all your derived classes have the exact same implementation (either in whole or in part), then it makes sense to place that implementation within the abstract class, thus ensuring consistency across all derivatives (and thus reducing maintenance). Each derived class can then explicitly call the base class method and optionally augment it with a more specific implementation where required, much as you would with a non-pure virtual method. The only real difference is that you are expected to provide an override for a pure-virtual method, whereas overriding a non-pure virtual method is always optional.

I thought its a development tool..

this is what i got from wiki ---

is a commercial (free version available), integrated development environment (IDE) product from Microsoft for the C, C++, and C++/CLI programming languages. It has tools for developing and debugging C++ code, especially code written for the Microsoft Windows API, the DirectX API, and the Microsoft .NET Framework.

There's no need to create a class to do this as std::string already does this and a lot more besides. The following class will do exactly as you've asked, but it's really just a wrapper for a std::string and achieves absolutely nothing.

#include<iostream>

class string{

public:

string(std::string s=""):m_str(s){}

string(const string& s):m_str(s.m_str){}

const std::string& get_string(){return(m_str);}

private:

std::string m_str;

};

int main()

{

string name1;

string name2("minu");

string name3(name2);

std::cout << "name1 = '" << name1.get_string().c_str() << "'" << std::endl;

std::cout << "name2 = '" << name2.get_string().c_str() << "'" << std::endl;

std::cout << "name3 = '" << name3.get_string().c_str() << "'" << std::endl;

return(0);

}

Output:

name1 = ''

name2 = 'minu'

name3 = 'minu'

An STD.

Here is an example:

// Example.cpp : Defines the entry point for the console application.

//

#include <stdio.h>

int main();

{

char example; /*Giving example the initialization char*/

printf("What value do you want example to have: ");

scanf("%s", example); /*This is where the value you have entered is being assigned to example*/

printf("Hello %s", example);

return 0;

}

Here is the program running:

What value do you want example to have: dude

Hello dude

True

In order to access a base class member the base class member must be declared protected or public. Private data is only accessible to members of the same class and to friends of the class. I'm not entirely sure what you mean by accessing from a database. A derived class does not require a database in order to access its base class members, it only requires protected access at the very least. Note that although you can declare derived classes to be friends of their base classes and thus allow private access, it would be an unusual design since base classes should never know anything about any of their derivatives.

It is an initialisation. You cannot assign values to a dynamic array until it has been initialised. Static arrays can be initialised at compile time. They can also be assigned at compile time.

void main()

{

// Compile time:

// =========

// Initialise a static array.

int arr1[10];

// Initialise and assign a static array.

int arr2[10] = {0,1,2,3,4,5,6,7,8,9};

// Runtime:

// ======

// Dynamic array (size unknown, no memory allocated)

int* pArr[];

// Initialise (size known, allocate memory, 40 bytes):

pArr = ( int* ) malloc( 10 * sizeof( int ));

// Assign (set values of elements):

int x;

for(x=0;x<10;++x)

pArr[x] = x;

// Uninitialise (release memory).

free( pArr );

return( 0 );

}

An exception is literally that: an exception. Exceptions are thrown when something that shouldn't happen does. For example, if you're trying to turn "Hi" into an Integer, you'll get a NumberFormatException (in Java.) If there is nothing in place to handle an exception, the program will crash. Try-catch blocks are used for exception handling within methods, and exception throwing is used to give out exceptions, or let a different method handle it.

Example program (Java):

class ex{

public static void main(String[] args){

String Strx = "5a";

int x = 0;

try{

x += Integer.parseInt(Strx);

}catch(NumberFormatException e){ // If Strx is not an Integer

x += Integer.parseInt("5");

}

System.out.println("The value of x is " + x); // The value of x is 5

}

}

Alternatively, you could remove the try-catch blocks, and simply write "public static void main(String[] args) throws NumberFormatException" in the 2nd line of the program.

All references must be non-null, therefore they will always have memory allocated to them. A reference is simply a non-null memory location that stores a specific type of variable, as determined by the reference's type. The reference name is an alias (a token) for the memory location, in much the same way that an array name is an alias for the starting address of the array.

A pointer variable is different in that memory must be set aside for the pointer variable itself, in addition to the memory it actually points to. On a 32-bit system, 4 bytes must be allocated to every pointer variable, to store the memory address that they point to, which could be null. But references only occupy the memory they actually refer to, which can never be null (a null reference will in fact render the program invalid).

string-literal

include <iostream>

using namespace std;

#define SIZE 10

template <class StackType> class stack {

StackType stck[SIZE];

int topOfStack;

public:

void init() {

topOfStack = 0;

}

void push(StackType ch);

StackType pop();

};

template <class StackType>

void stack<StackType>::push(StackType ob)

{

try {

if(topOfStack==SIZE) throw SIZE;

} catch(int) {

cout << "Stack is full.\n";

return;

}

stck[topOfStack] = ob;

topOfStack++;

}

template <class StackType>

StackType stack<StackType>::pop()

{

try {

if( topOfStack == 0)

throw 0;

} catch(int) {

cout << "Stack is empty.\n";

return 0;

}

topOfStack--;

return stck[topOfStack];

}

int main()

{

stack<char> stack1, stack2;

int i;

stack1.init();

stack2.init();

stack1.push('a');

stack2.push('x');

stack1.push('b');

stack2.push('y');

stack1.push('c');

stack2.push('z');

for(i = 0; i <3; i++)

cout << "Pop stack1: " << stack1.pop() << endl;

for(i = 0; i <4; i++)

cout << "Pop stack2: " << stack2.pop() << endl;

// demonstrate double stacks

stack<double> doubleValueStack1, doubleValueStack2; // create two stacks

// initialize the stacks

doubleValueStack1.init();

doubleValueStack2.init();

doubleValueStack1.push(1.1);

doubleValueStack2.push(2.2);

doubleValueStack1.push(3.3);

doubleValueStack2.push(4.4);

doubleValueStack1.push(5.5);

doubleValueStack2.push(6.6);

for(i = 0; i <3; i++)

cout << "Pop doubleValueStack1: " << doubleValueStack1.pop() << endl;

for(i = 0; i <4; i++)

cout << "Pop doubleValueStack2: " << doubleValueStack2.pop() << endl;

return 0;

}

Is an important thing to do.

96 + 93 + 98 = 287

Project - Settings - Link Tab Click on folder that has header files and librarys in the tree view Push OK

#include<iostream>

#include<vector>

#include<list>

#include<map>

#include<time.h>

int main()

{

srand ((unsigned)time(nullptr));

// Create a list of 100 values in the range 0 to 9.

std::cout << "Number list:\t";

std::list<size_t> numbers;

for (size_t i=0; i<100; ++i)

{

numbers.push_back (rand()%10);

std::cout << numbers.back() << ' ';

}

std::cout << '\n' << std::endl;

// Determine position(s) of each number.

std::map<size_t, std::vector<size_t>> map;

size_t pos = 0;

for (auto it=numbers.begin(); it!=numbers.end(); ++it)

map[*it].push_back(pos++);

// Print number, frequency and position(s).

for (auto it=map.begin(); it!=map.end(); ++it)

{

std::cout << "Number:\t\t" << (*it).first << std::endl;

std::cout << "Frequency:\t" << (*it).second.size() << std::endl;

std::cout << "Postions:\t";

const std::vector<size_t>& positions = (*it).second;

for (auto it=positions.begin(); it!=positions.end(); ++it)

std::cout << (*it) << ' ';

std::cout << '\n' << std::endl;

}

}

Yes, with type-cast (but I don't see why you should):

char *ptr = (char *)300;

the name of an identifier consists of letters and digits but name always starts with a letter.

conjunction...your welcome

#include <fstream>

int a,b;

a=a+b;

b=a-b;

a=a-b;

that's it simple