This document provides an overview of pointers and arrays in C++. It begins by explaining what pointers are, how they store memory addresses, and how to declare and assign values to pointer variables. It then covers arrays, including how they allow storing multiple values in contiguous memory locations that can be indexed. The document also discusses different types of arrays, such as one-dimensional, two-dimensional, and arrays of objects. Finally, it briefly introduces dynamic memory allocation using new operator at runtime.

1. UNIT 3
Pointer and Arrays
26/09/2015 Jitendra R. Patil 1

2. Pointers.
//Demonstration.
#include<conio.h>
#include<iostream.h>
void main()
{
int x ;
float y;
x = 10;
y = 20.0;
cout<<“Value’s of x and y = “<<x<<y;
getch();
}
26/09/2015 Jitendra R. Patil 2
4001 4002 4003
4004 4005 4006
4007 4008 4009
Memory
Every Block is
a memory cell
Cell no’s / Address
10
20.0
4007
x
4007
4002
y

3. Pointers
• A pointer is a variable that holds a memory address, usually
the location of another variable in memory
• The contents of (*) is used to declare a pointer
• Address-of operator (&) :
The & operator can find address occupied by a variable.
26/09/2015 Jitendra R. Patil 3

4. Example : Address-of Operator
#include <iostream>
using namespace std;
int main()
{
int var1 = 3;
int var2 = 24;
int var3 = 17;
cout<<&var1<<endl;
cout<<&var2<<endl;
cout<<&var3<<endl;
return 0;
}26/09/2015 Jitendra R. Patil 4

5. Pointer Declaration :
Syntax:
Data_type
* is used in declaration statements, it denotes a pointer
Defining a Pointer Variable
int *iptr;
iptr can hold the address of an int
26/09/2015 Jitendra R. Patil 5

6. Pointer Variables Assignment:
int num = 25;
int *iptr;
iptr = &num; //places the memory address of num into iptr
cout << iptr; // prints 0x4a00
cout << *itptr; // prints 25
26/09/2015 Jitendra R. Patil 6

7. Pointer Operator’s.
void main()
{ int *int_ptr;
float *float_ptr;
int x = 10 ;
float y = 20.0;
cout<<“Value’s of x and y = “<<x<<“ “<<y;
int_ptr = &x;
float_ptr = &y;
cout<<"int_ptr = "<<int_ptr;
cout<<"n float_ptr = "<<float_ptr;
cout<<"n value in int_pointer = "<< *int_ptr;
cout<<"n value in float_ptr = "<< *float_ptr;
getch();
}26/09/2015 Jitendra R. Patil 7
20.0
4002
10
4007
x y
Value at Address.
Address
Name of address

8. Pointers contd.
26/09/2015 Jitendra R. Patil 8
& Address of (Reference) Operator.
* Value At Address (Indirection) operator.
// Demonstration.
#include <iostream.h>
#include<conio.h>
void main ()
{
int variable ;
int *mypointer;
mypointer = &variable;
*mypointer = 50;
cout << "value in variable is " <<variable<<endl;
getch();
}
Address of variable = mypointer
50 = value at address
Value in variable is 50
50
3722
variable

9. Demo working of pointers
#include<iostream.h>
Void main()
{
int marks=70; //marks is an integer
int *p // p is a pointer
p=&marks; // p points to marks
cout<<“n Address is : ”<<p;
cout<<“n Value at that address is : ”<<*p;
}
26/09/2015 Jitendra R. Patil 9

10. void pointer
• In C++ General Purpose Pointer is called as void
Pointer.
• It does not have any data type associated with it
• It can store address of any type of variable
• Syntax
void *pointer_name
26/09/2015 Jitendra R. Patil 10

11. #include<iostream.h>
int main()
{
int i;
char c;
void *the_data;
i = 6;
c = 'a';
the_data = &i;
printf("the_data points to the integer value %dn", *the_data);
the_data = &c;
printf("the_data now points to the character %cn", *the_data);
return 0; }26/09/2015 Jitendra R. Patil 11

12. This Pointer
#include<iostream.h>
#include<conio.h>
class test
{
private:
int num;
public:
void get_val(num)
{
this->num=num;
}
26/09/2015 Jitendra R. Patil 12

13. Void print_val()
{
Cout<<“n The Value is”<<num;
}
};
void main()
{
test obj;
int num;
clrscr();
cout<<“”n Enter some Value : “;
cin>>num;
obj.get_val(num);
obj.print();
getch();
}
26/09/2015 Jitendra R. Patil 13

14. #include<iostream>
using namespace std;
/* local variable is same as a member's name */
class Test
{
private:
int x;
public:
void setX (int x)
{
// The 'this' pointer is used to retrieve the object's x
// hidden by the local variable 'x'
this->x = x;
}
void print()
{
cout << "x = " << x << endl;
}
};
26/09/2015 Jitendra R. Patil 14
int main()
{
Test obj;
int x = 20;
obj.setX(x);
obj.print();
return 0;
}

15. Pointer to object
#include<iostream.h>
#include<conio.h>
Class test
{
int a;
public:
test(int b)
{
a=b;
}
26/09/2015 Jitendra R. Patil 15

16. int get_val()
{
return a;
}
};
int main()
{
Test obj(100),*ptr_obj;
ptr_obj=&obj; //address of object is stored in pointer variable
cout<<“value obtained using pointer to object is…”<<endl;
cout<<ptr_obj->get_val()<<endl;
return 0;
}
26/09/2015 Jitendra R. Patil 16

17. Array
• Array is derived data type
• An array is a sequence of data item of homogeneous value(same
type).
• It is collection of variable of same type
• Specific element in array is accessed by an index
• All array consist of continuous memory locations
26/09/2015 Jitendra R. Patil 17

18. • Syntax: data_type array_name[size];
• int age[5]
26/09/2015 Jitendra R. Patil 18
Array Index
Elements of Array

19. Advantages
• Arrays can store a large number of value with single name.
• Arrays are used to process many value easily and quickly.
• The values stored in an array can be sorted easily.
• The search process can be applied on arrays easily.
26/09/2015 Jitendra R. Patil 19

20. #include <iostream.h>
void main()
{
int n[5];
cout<<"Enter 5 numbers: ";
for (int i = 0; i < 5; ++i)
{
cin>>n[i];
}
cout<<"First number: "<<n[0]<<endl;
cout<<"Last number: "<<n[4]<<endl;
}
26/09/2015 Jitendra R. Patil 20

21. Types of Arrays:
• One-Dimensional Array
• Two-Dimensional Array
• Multi-Dimensional Array
26/09/2015 Jitendra R. Patil 21

22. One-Dimensional Array
A type of array in which all elements are arranged in the form of a list is
known as 1-D array or single dimensional array or linear list.
Declaring 1-D Array:
data_type Variable[length]; e.g: int marks[5];
oData _type: Data type of values to be stored in the array.
oVariable: Name of the array.
oLength: Number of elements.
int marks 0 1 2 3 4
26/09/2015 Jitendra R. Patil 22

23. Array Initialization
• Size can be set from initial value list
int balance[5] = {1000.0, 2.0, 3.4, 17.0, 50.0};
• No default value
float pressure[10];
• Missing initialization values use zero
float pressure[10] = {2.101, 2.32, 1.44}
26/09/2015 Jitendra R. Patil 23

24. 26/09/2015 24
Accessing One Dimensional Array Elements
#include<iostream>
#include<conio.h>
Void main()
{
int a[10];
clrscr();
cout<<“enter the array”;
for (i=0;i<10;i++)
{
cin>>a[i];
}
cout<<“the entered array is”;
for(i=0;i<10;i++)
{
cout<<“Array = ”<<a[i]);
}
getch();
}
Array declaration
Taking values from user
Printing the values
OUTPUT
Enter the array
1 2 3 4 5 6 7 8 9 10
Entered array is
1
2
3
4
5
6
7
8
9
10
Jitendra R. Patil

25. Two-Dimensional Array
• Two-D array can be considered as table that consists of rows and columns.
• Each element in 2-D array is referred with the help of two indexes. One index
indicates row and second indicates the column.
Declaring 2-D Array:
Data_type Variable[row][column];
e.g: int arr[4][3];
o Data _type: Data type of values to be stored in the array. e.g: int arr[4][3];
o Variable: Name of the array.
o Rows : # of Rows in the table of array.
o Column : # of Columns in the table of array.
26/09/2015 Jitendra R. Patil 25

26. #include<iostream.h>
#include<conio.h>
int main()
{ clrscr();
int a[10][10];
int b[10][10];
int x, y, i, j;
cout<<"n Enter the number of rows and columns :::nn";
cin>>x>>y;
cout<<"nn Enter elements for Matrix A :::nn";
for(i=0;i<x;i++)
{
for(j=0;j<y;j++)
{
cin>>a[i][j];
}
cout<<"n";
}26/09/2015 Jitendra R. Patil 26
Accessing Two Dimensional Array Elements

27. cout<<"nnEnter elements for Matrix B :::nn";
for(i=0;i<x;i++)
{
for(j=0;j<y;j++)
{
cin>>b[i][j];
}
cout<<"n";
}
cout<<"nnMatrix A :nn";
for(i=0;i<x;i++)
{
for(j=0;j<y;j++)
{
cout<<"t"<<a[i][j];
}
cout<<"nn";
}
26/09/2015 Jitendra R. Patil 27

28. cout<<"nnMatrix B :nn";
for(i=0;i<x;i++)
{
for(j=0;j<y;j++)
{
cout<<"t"<<b[i][j];
}
cout<<"nn";
}
26/09/2015 Jitendra R. Patil 28

29. cout<<"nnAddition of Matrix A and Matrix B :nn";
for(i=0;i<x;i++)
{
for(j=0;j<y;j++)
{
cout<<"t"<<a[i][j]+b[i][j];
}
cout<<"nn";
}
getch();
return 0;
}
26/09/2015 Jitendra R. Patil 29

30. Array of Objects
26/09/2015 Jitendra R. Patil 30
#include<iostream.h>
#include<conio.h>
class rec
{
private:
int l, b;
public:
rec(int a, int c)
{
l=a; 09/09/2015
b=c;
}
void put()
{
cout<<"Area is : "<<l*b <<endl;
}
};
void main()
{
clrscr();
rec obj[3]={rec(3,6),rec(2,5),rec(5,5)};
cout<<"Displaying Areas of Rectangles :
n";
for(int i=0;i<3;i++)
obj[i].put();
getch();
}

31. #include<conio.h>
#include<string.h>
#include<iostream.h>
class student
{ private:
int s1,s2,s3,s4,s5,total;
char name[20],grade[10];
float per;
public:
int roll_no;
void input()
{
cout<<"n Enter the Name-";
cin>>name;
cout<<"n Enter the Roll No-";
cin>>roll_no;
cout<<"n M3 :";
cin>>s1;
cout<<"n OOT :";
cin>>s2;
cout<<"n ADE :";
cin>>s3;
cout<<"n MPMC :";
cin>>s4;
cout<<"n DSGT :";
cin>>s5;
cout<<"n";
total= (s1+s2+s3+s4+s5);
cout<<"n Total = "<<total;
per= total/5;
cout<<"n Percentage is " <<per;
}
26/09/2015 Jitendra R. Patil 31

32. void output()
{
if(per>=70)
strcpy(grade, "Distinction");
else if(per>=60)
strcpy(grade, "First Class");
else if(per>=40)
strcpy(grade,"Second class");
else if(per<40)
strcpy(grade, "Fail");
cout<<"nn";
cout<<"nt******MARKSHEET******";
cout<<"n";
cout<<"n Name :"<<name;
cout<<"n Roll No. : "<<roll_no;
cout<<"n M3 :"<<s1;
cout<<"n OOT :"<<s2;
cout<<"n ADE :"<<s3;
cout<<"n MPMC :"<<s4;
cout<<"n DSGT :"<<s5;
cout<<"n Total :"<<total;
cout<<"n Percentage :"<<per<<"%";
cout<<"n Grade :"<<grade;
}
};
26/09/2015 Jitendra R. Patil 32

33. void main()
{
int n,r,i;
student s[5];
cout<<"nEnter how many records u want to
insert:";
cin>>n;
for(i=0;i<n;i++)
s[i].input();
cout<<"n";
cout<<"nEnter the roll no for marksheet:-";
cin>>r;
for(i=0;i<n;i++)
{
if(s[i].roll_no==r)
{
s[i].output();
}
else
{
cout<<"n File doesnt Exit";
}
}
getch();
}
26/09/2015 Jitendra R. Patil 33

34. Dynamic Memory
• Memory in C++ program is divided into two parts
• The stack: All variables declared inside the function will take up
memory from the stack.
• The heap: This is unused memory of the program and can be used to
allocate the memory dynamically when program runs.
26/09/2015 Jitendra R. Patil 34

35. Memory Management Operator
• new operator
To allocate memory space using dynamically during runtime we can
use new operator
Syntax :
pointer_variable = new datatype
• delete operator
Free the memory space which is allocated with ‘ new’ we can use
delete operators
Syntax :
delete pointer_variable
26/09/2015 Jitendra R. Patil 35