l27 1d arrays

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A R R A Y S &S T R I N G S

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Arrays

Definition:

An array is a group of related data items that share

a common name.

The array elements are placed in a contiguous memory

locations.

A particular value in an array is indicated by writing an integer number called index number or subscript in a

square brackets

after the array name.

The least value that an index can take in array is0..

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Arrays

For example

We define an array named salary to represent a setof salaries of a group of employees.

Now the values or the salaries of employees

can be stored as follows.

salary[0]=10000, salary[1]=15000,

salary[2]=20000, salary[4]=10000,..etc.

wheresalary[0], salary[1], salary[2]

etc. respectively

represent the salaries of first, second, third employee.

7/13/2012 Department of CSE 3

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Arrays

If an array salary contains 5 integer values

(salaries) of employees then it is represented as

follows.

The elements are numbered from 0 to 4 since in

arrays the first index is always 0, independent of its

length.


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Arrays

ArrayDeclaration:

type name [size];

wheretypeis

avalid

data

type

(like

int,

float...)

nameisavalididentifier&

sizespecifieshowmanyelementsthearrayhastocontain.

sizefieldis

always

enclosed

in

square

brackets

[]and

takes

staticvalues.

Forexample

an

array

salarycontaining

5

elements

is

declared

as

follows

int salary [5];


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Arrays

One Dimensional Array

A linear list of fixed number of data items of same

type.

These items are accessed using the same name using

a single subscript. E.g. salary [1], salary [4]

A list of items can be givenone variable name

using only one subscriptand such a variable is

called a

single-subscripted variable

or a

one-

dimensional array.


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Arrays IDimensional

Rules for subscript:

A subscript can be integer constants, Integer variables like i,or expressions that yield integers.

Subscript of subscript is not allowed.

The Maximum subscript valueappearing in a program fora subscripted variable should not exceedthe declared one.

The subscript value ranges from 0 to one less than the

maximum size. For example, If the array size is 5 , then

the first subscript is 0, the second is 1 and so on the last

subscript is 4. In general ith element has subscript (i-1).


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Arrays1D

Totalsize:

TheTotalmemorythatcanbeallocatedto1Darrayis

computed

asTotal size =size *(sizeof(data_type));

where size numberofelementsin1Darray

data_type basicdatatype.

sizeof() is an unary operator which returns the size

of expression or data type in bytes.

Forexample,ifwewanttorepresentasetof5

numbersbyanarrayvariablen,thenwemay

declarethevariablenas int n[5];


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Arrays1D


If the values of array n

are 32, 27,64,18,95 then

these values are stored in n as follows.

n[0] n[1] n[2] n[3] n[4]

32 27 64 18 95

& n[0]

n

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Arrays1D


int n[5];

? ? ? ? ?

n[0] = 32; 32 ? ? ? ?

n[4] = 95; 32 ? ? ? 95

n[5] = 100; 32 ? ? ? 95100

Logically Not correct ! Out of range

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Initializingonedimensionalarray

At compile time

At run time[during program execution]

for (i=0; i

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Initializing one-dimensional array

(compile time)

type arrayname [size]={list of values}

type basic data type

arrayname name of the array.

sizemaximum number of elements and may be omitted.

List of values values separated by commas.

E.g.int number[3] ={ 0,0,0}or {0}

will declare the variable number as an array of size 3and will assign 0 to each element.


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Arrays1Dimensional

If the number of values in the list is less than

the number of elements, then only that many

elements will be initialized.

The statement

int age[ ] ={16, 25, 32, 48, 52, 65}; declares the age array to contain 6 elements

with initial values 16, 25, 32, 48,52, 65

respectively.


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Arrays1D


For example

int x[3] = {9,11,13};

cout

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Initializealltheelementsofan

integerarray

values

to

zero


int values[20];Begin for loop

Initialize counter

Set limit for counter

Increment counter

Initialize element in array

values

for ( )

values[i]=0;

int i=0; i

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Initializinganarraytothedaysof

eachmonthanddisplaysthosedays


const int NUM = 12;

for (int i=0; i < NUM; i++){

cout

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Programtoreadnelementsintoan

arrayand

print

it


cout>n;

couta[i];

cout

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Programtoaddtwoarrayelementsand

storethe

corresponding

elements

sum

in

anotherarray


cout>n; \\first array

for(i=0;i>a[i];

cout>m; \\second array

for(i=0;i>b[i];

if(m==n)

{

for(i=0;i

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Displayingelementsofanarrayin

reverseorder.

cout

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Writeaprogramto reverseanarray

usingonly

one

array

int a[20],i,j,n, temp;

cout>n;

couta[i];


Example:a[]={1,2,3,4,5}

Enter valuesn=5

12345

Reversedarray

5 4 3 2 1

Array

Reversedarray

a[0]=1 a[0]=5

a[1]=2 a[1]=4

a[2]=3 a[2]=3

a[3]=4 a[3]=2a[4]=5 a[4]=1

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Reversinganarray

j=n;

for(i=0;i

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cin>>n; // number of elements

couta[i];

cout>ele>>pos;

for(i=n;i>=pos;i--)

a[i]=a[i-1];

a[pos-1] = ele; //ele is inserted at the specified pos.

cout

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cout>n;

couta[i];

cout>pos;

for(i=pos; i

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Overview

1DArray:Syntax:type array_name[size];

MemoryRequirement:

Total size =size *(sizeof(data_type));

Initialization:

typearrayname[size]={list of values}

WriteandRead:

for(i=0;ia[i]; cout

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Searching&Sorting

SearchingTechniques LinearSearch

BinarySearch

SortingTechniques

BubbleSort

SelectionSort


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Linearsearch


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Linearsearch Example-2


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Linear search- Example-2


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int found=0;

cout>n;

for(i=0;ia[i];

}

cout>key;

WAPtosearchanelementinan

array


for(i=0; i

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BubbleSortAlgorithm


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BubbleSort Example


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BubbleSort Example


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for(i=0;i>a[i];

for(i=0;i

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Tobesolved


WAP to

Insert an element into a sorted array (new arrayshould be sorted one; find the pos in the sortedarray and insert there).

Delete an element from an array (elementshould be read; search it and delete it.)

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Insertanelementintoasorted

array


/ / f inding pos i t ion

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

if (ele>=a[i] elea[i])

pos = n;

/ / reposi t ion e lements a f ter pos

/ / inser t e le to pos

Example:insert3intoitsposition

a[]={1,2,4,5,6}

Newarrayafterinserting3:

a[]={1,2,3,4,5,6}

Readarrayelements&elementeletoinsert

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Tobesolved


WAP toFind the even & odd numbers stored in a given integer array

num. Display the original array num. Replace the even number

with its square and odd number with its cube in the same

array num. Display the new array num.[HINT:2 replaced with

4 & 3 replaced with 27]

Read two 1D arrays A & B. Merge A & B and store it in C. Array C

has to be sorted [use bubble sort] and displayed.

Now repeat the Merge process done for A & B (Q.2) by carrying

out the sort process (any sorting) while storing it in array A.[HINT: Read each element from array B and insert in

appropriate (sorted) position in array A]

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Summary

Arrays

1Dimensionalarrays(lists)

Problemson

1D

arrays

Searching

Sorting


l27 1d arrays

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