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ARRAYS

Sequence of memory elements of same

data type.

Sequence of 10 integers stored one afteranother in memory represents an array.

int a[10];

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ARRAYS

Fixed number of data items of same type.

Data items-Elements

Type int ,float and long etc.. Array of datatype character - strings

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ARRAY Declaration

a array of 10 integers

Square braces represents number of

elements

Array index starts from a[0] as shownbelow:

int a[10]Data type

Name of array

Size of array

Note: In C, array indices always begin with zero.

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Accessing ARRAY Elements

Array index points to particular elements in

an array.

Example: a[3]=54

a[7]=7

a[5]=21

a[10]=?

28 67917342178548615

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Usage of for loop

Commonly used to access array elements.

for(i=0;i

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Initialization of ARRAY

Can be initialized once they are declared.

int a[10]={28,15,86,54,78,21,34,7,91,67};

Values should be given in curly brackets. Less than 10 elements-0 will be filled.

Greater than 10 elements-excessive

element declared warning will be reported. List of values-separated by commas.

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Name of the array

Take the case where a is an array of 10

integers.

a-Name of the array

If a is used without any subscript in the printf,

what will be the output?

What will be the output of the following

statement?

printf(%d, sizeof(a));

Note : a =&a[0]

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ARRAYS

To handle matrix and tables, we need

array with multiple subscripts.

Two-dimensional array-two subscripts Row and column-starts with zero

2-D array can also be called as matrix.

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2-D ARRAY Declaration

35.5 40.5 45.5

50.5 55.5 60.5

65.0 70.0 75.0

80.0 85.0 90.0

float marks[4][3]Data type

Name of the array

Size of an array

4 rows

3 columns

0

1

2

3

0 21

Elements are accessed as follows:

Marks[0][0]=35.5

Marks[1][1]=55.5

Marks[2][1]=70.0

Marks[3][1]=85.0

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Storage of 2-D ARRAY

200

0

200

4

200

8

201

2

201

6

202

0

202

4

202

8

203

2

203

6

204

0

204

4

Marks[0][0]

Marks[0][1]

Marks[1][0] Marks[2][0] Marks[3][0]

Initialization:

Float marks[4][3]={ {35.5,40.5,45.5},

{50.5,55.5,60.5},

{65.0,70.0,75.0},

{80.0,85.0,90.0} };

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Passing ARRAY to a Function

/*Pass by Value*/

main( )

{

int i ;

int marks[ ] = { 55, 65, 75, 56, 78, 78, 90 } ;

for ( i = 0 ; i

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Passing ARRAY to a Function

/* Demonstration of call by reference */

main( )

{

int i ;

int marks[ ] = { 55, 65, 75, 56, 78, 78, 90 } ;

for ( i = 0 ; i

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Write a program to add two matrices using

function

Eg: function addmat()

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POINTERS AND ARRAYS

Facts to be considered:

Array elements are always stored in

contiguous memory locations.Pointer when incremented always points

to immediately next location of its type.

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POINTER TO ARRAY

main()

{

int num[ ]={24,34,12,44,56,17};

int i=0,*j;

j=&num[0];while(i

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POINTER TO ARRAY

Accessing array elements using pointer is

faster than accessing them by subscripts.

Should be accessed using pointers, if theelements are to be accessed in a fixed

order.

If there is no fixed logic, then subscript can

be used but pointer will be faster always.

Pointer notations:

num[i] = *(num+i) = *(i+num) = i[num]

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