Pointers are very useful construct of C++ programming language and what is more useful is 2d pointers.

The pointers are special variables pointing to a memory location or a variable where as an array is a collection of those variables. A 2d pointer is a pointer which is pointing to array of pointers.

e.g.

//Assign an array of 5 nameless pointers to a 2d pointer

int **pointer = new int*[5];



//then assign values to each array

for(int i=0;i<5; i++)

{

    pointer[] = new int[10];
}



//now we have a 2d pointer which can be also accessed as array

pointer[2][9] ; //this is third row and 10th element

Hey Guys.
This blog is related to a datatype in c++ that you'll find enormously helpful in your future assignments and semester projects.

So, to answer the very first question : "What is an Array ?"
Formally, An array is a series of elements of the same type placed in contiguous memory locations that can be individually referenced by adding an index to a unique identifier.
Confused ? I'd be surprised if you weren't.

Think of it like this, you have 5 numbers. Now as a beginner in C++, i'll make ten different variables and the store them in separately in these variables. Like this :

int a=1;
int b=5;
int c=11;
int d=19;
int e=30;

Now in order to access these stored values, we'll have to call each element by its distinct name.

By using array, we can use a single datatype to store multiple related elements within a closed structure. This makes it easier for us to access the values and acquire less space in the memory (10 elements in an array use less space than 10 different variables).
A typical way to initialize an array in c++ is :

datatype name [no. of elements] ;

//we shall now declare some arrays

//Suppose we want to make an array of 10 integer numbers. 
int array1[10];

// we can assign elements to the array like this:
int array1[10] = {2,4,6,8,10,12,14,16,18,20};
float array2[5] = {3.14, 2.27, 0.6990, 4.5, 123.4};
string array3[3] = {"Porsche", "Lamborghini" , "Maserati"};

//Note that in an array of 10 elements, values are indexed as 0-9


// now we can access the values in the array using their index number
print(array1[0]); // 0 is the index number of the element in the array
// we'll get 2 in the output

//similarly 

print(array2[3]); //This will print us 4.5
print(array3[1]); //This will print us Lamborghini


//In order to print every element of the array, we use for loop
for (int i=0; i<10; i++)
{
print(array1[i])
print(endl);
}
//This will print every element in the array1
//value of i will determine the index number of the element to be printed

//P.s. use cout statement instead of print command :)

The concept of arrays is very helpful for data structures.
You get a very good idea of memory management in c++. This concept will help you guys a lot in your 1st semester projects. Be it small databases, games, or anything. You'll always find arrays quite helpful.

Until next time.

The problem was diamond did not print odd rows with required spaces and stars.

#include <iostream>

using namespace std;
int main()
{
 int num,i=1,j=1,k=1,space,star;
 cout<<"Enter odd number of rows: ";
 cin>>num;
 if(num%2==0)
  num=num-1;

 space=num/2;
 star=1;
 cout<<endl;
 do
 { 
  if(space!=0)
   do //prints spaces
   {

    cout<<" ";
    k++;
   }while(k<=space);
   k=1;
   do //prints stars
   {
    cout<<"*";
    j++;
   }while(j<=star);
   j=1;
   cout<<endl;

   i++; //current row number for diamond
   if(i==(num/2)+1)
   {
    space=0;
    star=num;
   }

   if(i<=num/2)
   {
    star=star+2;
    space--;

   }

   if(i>1+num/2)
   {
    star=star-2;
    space++;
   }

   //star=2*i-1;
 }while(i<=num);
 return 0; 
}

sample output

Function pointers are a very powerful yet misunderstood aspect off programming languages.

Input in functions : type of input

#include <iostream>
#include <conio.h>

using namespace std;



int Factorial(int number)
{
 if (number <2)
 {
  return 1;
 }
 else
 {
  return (number * Factorial(number - 1));
 }
}

void main()
{
 int num;
 cout << "Enter Number: ";
 cin  >> num;

 int fact = Factorial(num);
 cout << "\nFactorial: " << fact;

 _getch(); //use 'getch()' if you are using version older than Visual Studio 2013.
}

Macros In C++ By Umair Sajid

Macros : are pre-processor directives Just As

                                #include<stdio.h>
             #include<graphic
             #include<conio.h>
             #include<malloc.h>
             #include<stdlib.h>
             #include<dos.h>
             #include<iostream> 

but In Above Directive Directs The Compiler to include followings library functions . However We Are Concern with the Macros.

Syntax:               #define ADD x+y

  Actually They Can Be think As Same As Functions But Just Defined Before Main and with A little difference of Syntax and working. In a Nutshell  You can Call Macros as Functions Using As A Variable

Use: Macros In C++ Is Usually Used Where We Required Fast Execution. However The Same Work Can be Done By Using Functions But The Function can pass arguments and require a return_type of the Integers or Result Return.

Lets Come To A Simple Program That prompt the user to enter a number and prints its cube and square using macros.

#include<iostream>
#define SQUARE num*num      // MACROS
#define CUBE num*num*num    // MACROS
using namespace std;
int main()
{
    int num;
    cout<<"\n\t\tEnter A Number : "; // prompt to enter a number
    cin>>num;               // store it in num

    cout<<"\n\t\tThe Square of "<<num<<" is : "<<SQUARE<<"\n";   // Just as function call we have used
    cout<<"\n\t\tThe Cube of "<<num<<" is :"<<CUBE;                     // macros
    cout<<"\n\n";
    cout<<"\n\t\t***THANKYOU PC Umair Sajid ****\n\n";
}

C++ has a great feature of increment and decrement operators.
increment means to increase value and decrement means to decrease value.

e.g.

int apples = 10 ; 

apples = apples + 1 ;     //increments by 1

apples = apples - 1 ;     //decrements by 1 

//now apples ==10



//in C++ we can do this more easily with increment and decrement operators.



apples++; //increments

apples--; //decrements



Type of increment/decrement operators



PostFix: it changes value of variable after rest of the statement is executed.

Prefix: it changes value before any other calculation.



e.g.



int oranges = apples++;

/*

oranges will now be 10 and after execution apples value will increase by 1 so  apples=1

*/

//similarly this will result in 10 oranges and 10 apples

oranges = --apples; //first apples will be set to 10(11-1) and then oranges = apples = 10;



/* We can see in the above example that --apples/++apples or vice versa changes the value of apples. The compiler reads the following line : */
oranges = ++apples ;
// change apples = apples+1. Then set the value of Oranges = apples (new value)


/*So the statement has altered the original value of apples.
// If we do not want to change the value of apples and still set the value of oranges, then we do the following : */


oranges = apples+1;
//So the value of apples remains intact and +1 value is set for oranges :)

                Use of a Simple Void Function 

Some basic understanding to use functions:

Other types of outputs:

without argument

Many of you has question in your mind that how to declare and define Pointer to Array in C++.

I 'll show how?

#include <iostream>

#include <conio.h>




using namespace std;




void main()

{

//int pointer to array declaration.

int *pointer_array[10];

//defining pointer to array.

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

 {

 pointer_array[i] = new int[5];

 for (int j=0; j<5; j++)

 pointer_array[i][j] = -1;

 } 

 getch();

}

In computer science, selection sort is a sorting algorithm, specifically an in-place comparison sort. It has O(n²) time complexity.
The algorithm divides the input list into two parts: the sublist of items already sorted, which is built up from left to right at the front (left) of the list, and the sublist of items remaining to be sorted that occupy the rest of the list. Initially, the sorted sublist is empty and the unsorted sublist is the entire input list. The algorithm proceeds by finding the smallest (or largest, depending on sorting order) element in the unsorted sublist, exchanging it with the leftmost unsorted element (putting it in sorted order), and moving the sublist boundaries one element to the right.
For more detail use Wiki... Selection Sort

#include <iostream>
#incl

ude <conio.h>

using namespace std;//Selection Sort Function



void Ssort(int *a,int length)

{



int temp;

for(int i=length-1;i>0;i--)

{

int first=0;

for(int j=1;j<=i;j++)

if(a[j]>a[first])first=j; temp=a[first];a[first]=a[i];a[i]=temp;}

}



void main()

{



int arr[10];

int temp[10];

arr[0]=100;

arr[1]=33;

arr[2]=43;

arr[3]=26;

arr[4]=46;

arr[5]=88;

arr[6]=52;

arr[7]=17;

arr[8]=53;

arr[9]=77;



for(int i=0;i<10;i++)

{

temp[i]=arr[i];

cout<<arr[i]<<",";

}



//calling selection sort function

Ssort(temp,10);



//Displaying the result.

cout<<endl<<endl;



for(int i=0;i<10;i++)

cout<<temp[i]<<",";

getch();

}

//code by http://CppQA.blogspot.com
//we are community of developers focusing on help for new programmers
#include <iostream>
using namespace std;
#define CHAR_BIT 8

/*Function to find minimum of x and y*/
int min(int x, int y)
{
  return  x + ((y - x) & ((y - x) >>
            (sizeof(int) * CHAR_BIT - 1)));
}

/* Function to find minimum of 3 numbers x, y and z*/
int smallest(int x, int y, int z)
{
    return min(x, min(y, z));
}

int main()
{
   int x = 1, y = 100, z = 90;
   cout << "Minimum of 3 numbers is " << smallest(x, y, z) << endl<<"http://CppQA.blogspot.com"<<endl;
   return 0;
}

you can fork this code on ideone.com

Swapping means to interchange values of usually two variables and is done using third temp variable e.g.

int var1 = 10, var2 = 20;
int temp = var2;
var2 = var1;
var1 = temp;
//now var1 = 20 and var2 = 10
//hence values have been swapped

But take a look at code swapping without use of third variable, this trick will come handy in future assignments

int var1 = 10, var2 = 20;
var1 = var1 * var2;
var2 = var1 / var2;
var1 = var1 / var2;
//now var1 = 20 and var2 = 10
//hence values have been swapped

For the person who can explain this code to me and post a solution using (^) operator, there is a GENUINE MICROSOFT VISUAL STUDIO KEY ;)
You can post a request for guest post in comments, anywhere

#include <iostream>
using namespace std;
#define CHAR_BIT 8

/*Function to find minimum of x and y*/
int min(int x, int y)
{
  return  y + ((x - y) & ((x - y) >>
            (sizeof(int) * CHAR_BIT - 1)));
}

/* Function to find minimum of 3 numbers x, y and z*/
int smallest(int x, int y, int z)
{
    return min(x, min(y, z));
}

int main()
{
   int x = 12, y = 15, z = 5;
   cout << "Minimum of 3 numbers is " << smallest(x, y, z) << endl;
   return 0;
}

(Continued From Special Diamonds Part 1) Part 2; Here will use 2 loops inside one loop so that it is easy to print shape in less loops and coding; It is simple because the loop we used for triangle in first page is going to be repeated in this loop only we will change the size alignment of shapes upside down;

A post by Usman of BESE 19 at MCS.

The simple program logic for Diamond printing program:

Part 1;

int i,j,rows,size;
cin>>rows;     //take input
size = rows;     //give the initial size of shape which is decreasing
size = 1;      //if shape is increasing then size is 1
do      //it will run row’s * time
{ j=size;      //it will change size of rows constantly
           do     //this loop is always as this format whatever shape is decreasing or increasing as it has to print a line of given width anywhere required
 {
                        cout<<”required character”; // do not put endl here as it is a continues line
                               j--;
               } while (j < size);
size--;     //if size of shape is decreasing downwards
size++;    //if size of shape is increasing downwards
cout<<endl; 
}while (i<given rows);

Please visit next part at Special Diamonds Part 2