structure and pointer

WELCOME TO OURPRESENTATION

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STRUCTURE AND POINTER

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Prepared By:

Md. Tanvir HossainDepartment of CSEDaffodil International University

Jakir HossainDepartment of CSEDaffodil International University

What is structure?

Overview..

Structure With Function Arrays of structures What is a Pointer ? Why Pointers ?

Operators used in Pointers Relation Between

Structure And Pointer

STRUCTURE AND POINTER

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What is structure?

A structure is a collection of variables of different data types under a single name.

It is a collection of heterogeneous data.It can have integer, float, double or character

data in it.The variables are called members of the

structure.The structure is also called a user-defined data

type.

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Defining a Structure :

struct structure_name{data_type

member_variable1;data_type

member_variable2;………………………………;data_type

member_variableN;};

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struct student{char name[20];int roll_no;float marks;char gender;long int phone_no;};

• Multiple variables of struct student type can be declared as:

struct student st1, st2, st3;

Example :

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struct student{char name[20];int ID;float CSE_marks;char gender;long int phone_no;};

void main(){ struct student st1={"Ishtiaque",5482,13.5,'M',16021548}; struct student st2={“Rony,4288,15,'F',19845321};

printf ("Name: %s ID: %d CSE Marks: %.1f Gender: %c Phn: %d \n",st1.name,st1.ID,st1.CSE_marks,st1.gender,st1.phone_no);

printf ("Name: %s ID: %d CSE Marks: %.1f Gender: %c Phn: %d \n",st2.name,st2.ID,st2.CSE_marks,st2.gender,st2.phone_no);}

Example :

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Sample Output :

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Structure With Function :

We will consider four cases here:

Passing the individual member to functionsPassing whole structure to functionsPassing structure pointer to functionsPassing array of structure to functions

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Passing the individual member to functions :

Structure members can be passed to functions as actual arguments in function call like ordinary variables.

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Passing whole structure to functions :

Whole structure can be passed to a function by the syntax:

function _ name ( structure _ variable _ name );

The called function has the form: return _ type function _ name (struct tag _ name

structure _ variable _ name) { …………; }

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Passing structure pointer to functions :

In this case, address of structure variable is passed as an actual argument to a function.

The corresponding formal argument must be a structure type pointer variable.

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Arrays of structures• An ordinary array: One type of data

• An array of structs: Multiple types of data in each array element.

0 1 2 … 98 99

0 1 2 … 98 99

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Arrays of structures :• We often use arrays of structures.• Example:

StudentRecord Class[100];strcpy(Class[98].Name, “Bangladeshi man");Class[98].Id = 12345;strcpy(Class[98].Dept, "COMP");Class[98].gender = 'M';Class[0] = Class[98];

Bangladeshi man

12345 M

COMP

. . .

0 1 2 … 98 99

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‘*’ , ‘&’ Pointer

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In a generic sense, a “pointer” is anything that tells us where something can be found. Addresses in the phone book URLs for webpages Road signs

What is a Pointer ? A variable that holds a memory address.This address

is the location of another object in the memory

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Why Pointers ?They allow you to refer to large data structures in

a compact way

They facilitate sharing between different parts of programs

They make it possible to get new memory dynamically as your program is running

They make it easy to represent relationships among data items.

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Operators used in Pointers

* &AddressDereferencing

(Address of)(Value of)

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Int i=3;

Address of ‘i’ Value of ‘i’

X1000 x1004 x1008 x100c x1010 x1014

variablei

3(Value of i)

Address of i

‘&i’ ‘*i’

The value ‘3’ is saved in the memory location ‘x100c’

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Pointer Assignment

Int i = 1 , *ip ; //pointer declaration ip = &i ; //pointer assignment*ip = 3 ; //pointer assignment

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Lets Take an Example and See

how pointers

work

#include<stdio.h>void main(){int i=3;int *j;j=&i;printf(“i=%d”,i);printf(“j=%d”,j);}

23X1000 x1004 x1008 x100c x1010 x1014

3Memory

variables Int iInt *j

Int i=3;Int *j;j = &i;

x100c

Create an integer variable ‘i’ and initialize it to 3

Create a pointer variable ‘j’- create value of ‘j’

Initialize the pointer value of ‘j’ to the address of ‘i’

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Arrays and pointers are closely related

Array name is like a constant pointer

Pointers can do array subscripting operations

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Relation Between Structure And Pointer :

Structure and pointer are interrelated.We Avaiable Use Structure and pointer at together.Such as…….Linked listQueueStack

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A structure's member can be accesssed through pointer in two ways:Accessing structure's member through pointer

Referencing pointer to another address to access memory

Using dynamic memory allocationReferencing pointer to

another address to access memory

Using dynamic memory allocation

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Overview..

Structure and pointer are the two important element of c programming. For solving many kind of problem we use this……………..

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AnyQuestion?

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Thank You !