CHAPTER 6 ARRAYS IN C++2nd Semester 1433 -1434

King Saud University College of Applied studies and Community ServiceCSC 1101By: Fatimah AlakeelEdited By: Mashael almutlaq Noor Alhareqi

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Array - One Dimensional Array A one dimensional array

is a list of related variables have the same data type and the same name .

Represented as a group of consecutive memory locations .

To refer to a particular location or element in the array, we specify the name of the array and the position number of the particular element in the array.

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Defining Arrays When defining arrays, specify :

1. Array Name .2.Type of array .3. size of the arrays .

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Defining Arrays The general form :

Type array_Name [ size ];

Type declares the base type of the array that determines the data type of each element in the array .

Size defines how many elements the array will hold. The Size must be an integer constant greater than zero.

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Defining Arrays - Examples-

int A[10];• An array of ten integers .

Char str[20];• An array of twenty characters .

int a[ 100 ], b[ 27 ] ; • Defining multiple arrays of same type .

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Defining Arrays - Examples- The Size must be an integer constant

greater than zero.

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Define an array temperature of 5 elements contains float numbers , array size 5 :

double temperature [5];

Initialize it with these numbers : 12.3 , 7.5 , 65 , 72.1, 87.5 .

double temperature [5] = {12.3 , 7.5 , 65 , 72.1, 87.5 } ;

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Defining and Initializing an Array

Elements

7.5

65.0

72.1

87.5

12.3temperature [0]

temperature [1]

temperature [2]

temperature [3]

temperature [ 4 ]

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double temperature [5] = {12.3 , 7.5 , 65 , 72.1, 87.5 };

Index

Defining and Initializing an Array

Initializing Arrays int N[ ] = { 1, 2, 3, 4, 5 };

If size omitted, the size is determined from the 5 initializers . int N[5] = { 0 } ; int B[20] = {2, 4, 8, 16, 32};

Unspecified elements are guaranteed to be zero . If not enough initializers, rightmost elements become 0 .

int C[4] = {2, 4, 8, 16, 32}; Error — compiler detects too many initial values . C++ arrays have no bounds checking .

int D[5] = {2*n, 4*n, 8*n, 16*n, 32*n}; Automatically only ; array initialized to expressions .

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Accessing Array Elements An individual element within array is

accessed by use of a subscript (index) that describes the position of an element in the array , it must be an integer or integer expression .

Array named c of size n: c[0],c[1],...,c[ n–1 ]

int A[10];A[0], A[1], …, A[9]

In C++ , all array have zero as the index of first element .

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1. Initialize arrays with the variable declaration .

double temperature [ 5 ] = { 12.3 , 7.5 , 65 , 72.1 , 87.5 } ;

2. Use Assignment statements .

3. Read input values into the array from the keyboard.

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Get values into array elements

Accessing Array Elements Array elements are like normal

variables :

temperature [3] = 12.7 ; cin >> temperature [3] ;

or N = 3;

temperature [N] = 12.7;

temperature [5-2] == temperature [3] == temperature [N]

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Assigning Values You cannot assign one array to another :

int a[10] , b[10] ; a=b ; //error … illegal

Instead, we must assign each value individually .

We can use them as values in assignment statements:

char str[ ] =“Hello amal”; str[6] = ‘A’;

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Examples For example, if we assume that variable a is equal to 5 and that variable b is equal to 6, then the following statement adds 2 to array element c[11].

To print the sum of the values contained in the first three elements of array c, we’d write

To divide the value of c[6] by 2 and assign the result to the variable x, we would write

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Manipulating Arrays For loops are used to:

Initializing array elements . Reading elements . Printing elements . Performing operations :

Sum elements . Find largest/ smallest element . Search for an element . Sort elements .

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Initializing Array Elements : To access all elements of an array a for

loop is used. It will start from index 0 to the last element in the array which has an index of array size-1.

Define and initialize array a of size 10 with zeros

int a[10],index; for(index =0; index <= 9; index++) a[index] = 0;

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Manipulating Arrays

Reading Elements :

for (index =0; index <= size-1; index++ ){

cout << “Enter value : ”; cin >> a[index];}

Printing Elements :

for (index =0; index <= size-1; index++)cout << a[index];

Sum Array elements Elements :

for (sum = 0, j=0; j < size; j++)sum += a[j];

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Manipulating Arrays

Examples All of the following are valid:• score[0] = 4 ; • score[0] += 7 ;• score[0] = x + y ;• x = y – score[0] ;• score[2] = score[1] + 5 * score[0] ;• score[ j ] = score[ j + 1] ;

Note: index can be any integral expression.

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Example –sum of elements19

1 /* Fig. 6.4: fig06_04.c 2 Initializing an array with an initializer list */ 3 #include <iostream > 4 using namespace std; 5 /* function main begins program execution */ 6 int main() 7 { 8 /* use initializer list to initialize array n */ 9 int n[ 10 ] = { 32, 27, 64, 18, 95, 14, 90, 70, 60, 37 }; 10 int i; /* counter */ 11 12 cout<< "Element Value"<< end1 13 14 /* output contents of array in tabular format */ 15 for ( i = 0; i < 10; i++ ) { 16 cout<< i<< "\t"<< n[ i ]<< endl ; 17 } /* end for */ 18 19 return 0; /* indicates successful termination */ 20 21 } /* end main */

Element Value 0 32 1 27 2 64 3 18 4 95 5 14 6 90 7 70 8 60 9 37

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1 /* Fig. 6.3: fig06_03.c 2 initializing an array */ 3 #include <iostream > 4 using namespace std; 5 /* function main begins program execution */ 6 int main() 7 { 8 int n[ 10 ]; /* n is an array of 10 integers */ 9 int i; /* counter */ 10 11 /* initialize elements of array n to 0 */ 12 for ( i = 0; i < 10; i++ ) { 13 n[ i ] = 0; /* set element at location i to 0 */ 14 } /* end for */ 15 16 cout<<"Element Value" << end1 ; 17 18 /* output contents of array n in tabular format */ 19 for ( i = 0; i < 10; i++ ) { 20 cout<< i<<"\t"<<n[ i ]<<endl ; 21 } /* end for */ 22 23 return 0; /* indicates successful termination */ 24 25 } /* end main */

Element Value 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0

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1 /* Fig. 6.5: fig06_05.c 2 Initialize the elements of array s to the even integers from 2 to 20 */ 3 #include <iostream > 4 #define SIZE 10 /* maximum size of array */ 5 6 /* function main begins program execution */ 7 int main( void ) 8 { 9 /* symbolic constant SIZE can be used to specify array size */ 10 int s[ SIZE ]; /* array s has SIZE elements */ 11 int j; /* counter */ 12 13 for ( j = 0; j < SIZE; j++ ) { /* set the values */ 14 s[ j ] = 2 + 2 * j; 15 } /* end for */ 16 17 cout <<"Element Value" << end1 ; 18 19 /* output contents of array s in tabular format */ 20 for ( j = 0; j < SIZE; j++ ) { 20 cout<< i<<"\t"<<n[ i ]<<endl ; 22 } /* end for */ 23 24 return 0; /* indicates successful termination */ 25 26 } /* end main */

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