Lecture 15: Projects Using Similar Data

What is an Array?An array is a data structure consisting of related data items of the same type.Stored in a group of memory locationsDefining arrays

int arrayName[ 100 ];

Examples int a[5]; float b[120], x[24];

……

a[0] 5

memory

10

15

3

23

a[1]

a[2]

a[3]a[4]

Specifying the type of each element

Name of the array

The number of the elements

Passing Arrays to FunctionsThe name of an array evaluates to the address of the first element of the array.Passing arrays

To pass an array argument to a function, specify the name of the array without any brackets

int anArray[100];aFunction( anArray, 100 );

Array size usually passed to functionFunction knows where the array is stored

Modifies original memory locations

Defining Function with Array ParametersThe function’s parameter list must specify that an array will be received.

void aFunction( int ary[ ], int size ) {

……..}

Function prototype void aFunction( int ary[ ], int size );

Parameter names optional in prototype int ary[ ] could be written int [] int size could be simply int

The header of the function

The size of the array is NOT required.

void aFunction( int [ ], int );

Defining Function with Array Parameters

Using the type qualifier const.void aFunction( const int ary[ ], int size )

The modification of the array elements are NOT allowed.

Any attempt to modify an element of the array in the function body results in a compile-time error.

The header of the function

Passing Array Elements

Passed by call-by-value.Array elements are like normal variables

Pass subscripted name to functionvoid modifyArrayElement( int arrayElement );

int array[ 10 ] = {0};

modifyArrayElement( array[1] );

modifyArrayElement( array[8] );

Practice Question

Q. Which is the right way to pass an integer array argument ary to the following function?

void func( int a[] );int ary[25];

A. func( ary[25] );B. func( ary[] );C. func( ary );D. func( ary[0] );

Solu

tion

: C

Practice Question

Q. Which is NOT the right way to pass an integer array argument ary to the following function?

#include<stdio.h>#define SIZE 5;void func( int a[], int x );int main( void ){int b[SIZE] = {1, 2, 3, 4, 5};

func(b, b[1]);printf(“%d %d\n”, b[0], b[1]);return 0;}

void func( int a[], int x){int k;for (k = 0; k < SIZE; k++) a[k] *= 2;x *= 2;}

A. 1 2B. 2 4C. 2 8D. 1 4

Solu

tion

: B