ONE-DIMENSIONAL ARRAY TWO-DIMENSIONAL ARRAY

STRUCTURED DATA TYPE ARRAYS IN C++

ObjectivesDeclaration of 1-D and 2-D Arrays

Initialization of arrays

Inputting array elements

Accessing array elements

Manipulation of 1-D array elements (Sum, Product, Average,

Maximum/Minimum, Linear search)

Manipulation of 2- D array elements (Sum of row elements, column

elements, diagonal elements, finding maximum/minimum values)

An Array is a series of elements of the same data type placed

in contiguous memory locations referred by a common name.

The elements of array are referred by their Subscript number

or Index number which starts from zero.

Array

One Dimensional Array

One Dimensional or Single Dimensional Arrays comprises of definite number of homogeneous elementsSyntax to declare 1-D Array is :

datatype NameOfArray [ SizeOfArray] ;

Example:int Num[5]; // Num can store 5 integers char Str[10]; // Str can store a single string

101 103 105 107 109

Num[0] Num[1] Num[2] Num[3] Num[4]

H A N S R A J \0Str[0] Str[1] Str[2] Str[3] Str[4] Str[5] Str[6] Str[7] Str[8] Str[9]

Memory Usage of 1-D Array

Memory Consumed by 1D Array = Size of Data Type X No. of Elements

Example:

int Num[5]; = 2 Byte X 5 Elements = 10 Bytes

char Str[10]; = 1 Byte X 10 Elements = 10 Bytes

float Amt[3]; = 4 Byte X 3 Elements = 12 Bytes

Two Dimensional Array

Two Dimensional comprises of an Array of elements each of which is itself an Array

Syntax to declare 2-D Array is :

datatype NameOfArray [ NoOfRows] [ NoOfColumns] ;

Example:

int arr[4][4];

COL=0 COL=1 COL=2 COL=3

ROW=043

arr[0] [0]

22arr[0] [1]

16arr[0] [2]

34arr[0] [3]

ROW=167

arr[1] [0]

26arr[1] [1]

98arr[1] [2]

12arr[1] [3]

ROW=254

arr[2] [0]

24arr[2] [1]

89arr[2] [2]

64arr[2] [3]

ROW=323

arr[3] [0]

34arr[3] [1]

78arr[3] [2]

29arr[3] [3]

Memory Usage of 2-D Array

Memory consumed by 2D Array = Size of Data Type X No. of Rows X No. of Columns

Example:

int Num[4][3] ; = 2 Byte X 4 Rows X 3 Cols = 24 Bytes

char Str[5][10]; = 1 Byte X 5 Rows X 10 Cols = 50 Bytes

float Amt[[5][4]; = 4 Byte X 5 Rows X 4 Cols = 80 Bytes

Initialization of 1-D Array ElementsAt the time of declaration array elements can be initialized as follows:int Num[4] = { 54,65,72,34 };char Str[4] = { ‘C’, ‘+’ , ’+’ , ’\0’ };char Str[4] = ”C++”;

Note:

int A[5] = {21, 45, 67, 43, 23, 87, 90, 100};// Error because number of values between braces {} is greater than the array sizeint A[5] = {34, 56, 22}; // If less initializers , the remaining elements are set to default values i.e A[3] = 0, A[4] = 0

Unsized Array Initialization of 1-D Arrays :

If you skip the size of the array in the array initialization statement, compiler automatically creates an array big enough to hold all initializers present in the statement.int Arr[] = { 500,600,700 };char Str[] = ”Hello”;

54 65 72 34Num[0] Num[1] Num[2] Num[3]

C + + \0Str[0] Str[1] Str[2] Str[3]

500 600 700Arr[0] Arr[1] Arr[2]

H e l l o \0Str[0] Str[1] Str[2] Str[3] Str[4] Str[5]

Initialization of 2-D Array Elements

Example:int arr[2][3]={43,22,16,67,26,98};// can store a 2x3 Matrix of Integers

char arr[2][5]={ ″AMAN ″, ″RAMA″ };

// can store 2 Strings of maximum 5 chars each

Unsized Array Initialization of 2-D Arrays :2-D Arrays can be initialized in an unsized manner, but you can skip the Row size only and the Column size needs to be mentioned in the declaration.int arr [][2]={500,600,700,800,900};

Advantage of Unsized Array Initialization It allows you to change the array content i.e lengthen or shorten the number of elements without resizing the Array

COL=0 COL=1 COL=2

ROW=043

arr[0] [0]

22arr[0] [1]

16arr[0] [2]

ROW=167

arr[1] [0]

26arr[1] [1]

98arr[1] [2]

COL=0 COL=1

ROW=0500

arr[0] [0]

600arr[0] [1]

ROW=1700

arr[1] [0]

800arr[1] [1]

ROW=2900

arr[2] [0]

0arr[2] [1]

COL=0 COL=1 COL=2 COL=3 COL=4

ROW=0A

arr[0] [0]

Marr[0] [1]

Aarr[0] [2]

Narr[0] [3]

\0arr[0] [4]

ROW=1R

arr[1] [0]

Aarr[1] [1]

Marr[1] [2]

Aarr[1] [3]

\0arr[1] [4]

Inputting Array Elements in 1-D Arrays

#define MAX 5

Accepting input in 1-D integer array:int num[MAX];

//can store MAX integersfor(int i=0;i<MAX;i++)

cin>>num[i];

Accepting input in 1-D character array:char arr[MAX]; //can store only one string containing MAX-1 chars

cin>>arr;or

gets(arr);

Num[0] Num[1] Num[2] Num[3] Num[4]

Str[0] Str[1] Str[2] Str[3] Str[4]

Inputting Array Elements in 2-D Integer Arrays

#define MAX 4

Accepting input in 2-D integer array:

int arr[MAX][MAX];//can store a matrix of MAX * MAX integers

//Row wise input:for(int i=0;i<MAX;ifor(int j=0;j<MAX;j++)

cin>>arr[i][j];

//Column wise input:for(int j=0;j<MAX;j++)for(int i=0;i<MAX;i++)

cin>>arr[i][j];

Col 0 Col 1 Col 2 Col 3

Row 0

Row 1

Row 2

Row 3

Col 0 Col 1 Col 2 Col 3

Row 0

Row 1

Row 2

Row 3

Inputting Array Elements in 2-D Character Arrays

#define MAX 4

Accepting input in 2-D character array:

char arr[MAX][MAX];//can store MAX strings - each containing MAX-1 chars

for(int i=0;i<MAX;i++)gets(arr[i]);

String 0S

arr[0] [0]

Aarr[0] [1]

Tarr[0] [2]

\0arr[0] [3]

String 1M

arr[1] [0]

Aarr[1] [1]

Tarr[1] [2]

\0arr[1] [3]

String 2X

arr[2] [0]

Aarr[2] [1]

Tarr[2] [2]

\0arr[2] [3]

String 3C

arr[3] [0]

Aarr[3] [1]

Tarr[3] [2]

\0arr[3] [3]

Assignment Statement

Array elements can be assigned a new value during the execution of the program. Example:

int A[5];A[3] = 4;A[1] = A[3] + 10;A[4] = A[1] + A[3];A[2] = 7 – A[4];A[0] = A[1] + A[4];

4

A[0] A[1] A[2] A[3] A[4]

14 4

A[0] A[1] A[2] A[3] A[4]

14 4 18

A[0] A[1] A[2] A[3] A[4]

14 -11 4 18

A[0] A[1] A[2] A[3] A[4]

32 14 -11 4 18

A[0] A[1] A[2] A[3] A[4]

Passing 1-D arrays to functions

Arrays are always automatically passed by reference. Thus when you specify the name of a 1-D integer array as an argument to a function,

only the starting address of the array i.e the address of the 0th element is received by the function.

This function has no means to find out how many elements are present in the array, since integer arrays are not terminated by null character ‘\0’

Therefore you need to pass a 2nd separate argument to the called function which is the size of the array.

Function Prototype should be:

returndatatype function_name ( datatype arrayname[], int NoOfElements );

Sum of elements of 1-D array#include <iostream.h>#define MAX 10int SUM (int[], int); //prototypevoid main(){ int A[MAX], N, Ans;

cout << “Enter the number of locations ”; cin >> N;for (int I = 0; I <N; I++)

{ cout << “Enter data in A[“ << I << “] = “;cin >> A[I];

}Ans = SUM (A, N);cout << “Sum of elements = “ << Ans;

}int SUM( int Arr[], int n){ int S = 0;

for (int I = 0; I < n; I++)S = S + Arr[I];

return S; }

Product of elements of 1-D array#include <iostream.h>#define MAX 10int PROD (int[], int);void main(){ int A[MAX], N, Ans;

cout << “Enter the number of locations ”; cin >>N;

for (int I = 0; I < N; I++){ cout << “Enter data in A[“ << I << “] = “;

cin >> A[I];}

Ans = PROD (A, N);cout << “Product of elements = “ << Ans;

}int PROD( int Arr[], int n){ int P = 1;

for (int I = 0; I < n; I++)P = P * Arr[I];

return P; }

Average of elements of 1-D array#include <iostream.h>#define MAX 10float Average (int[], int); //prototypevoid main(){ int A[MAX], n;

float Ans;cout << “Enter the number of locations ”; cin >> n;

for (int I = 0; I < N; I++){ cout << “Enter data in A[“ << I << “] = “;

cin >> A[I];}

Ans = Average (A,N);cout << “Average of elements = “ << Ans;

}float Average ( int Arr[], int n){ int S = 0;

for (int I = 0; I < n; I++)S = S + Arr[I];

return float(S)/n; }