Department of Information Technology Computer Programming Problem Solving

Department of Information Technology Computer Programming & Problem Solving www. husamo. wordpress. com Ch 2 Arrays KIC/Computer Programming & Problem Solving 1

Outline Ø Introduction Ø Arrays Ø Declaring Arrays Ø Examples Using Arrays Ø Multiple-Subscripted Arrays 08/01/2022 2 KIC/Computer Programming & Problem Solving

Objectives In this chapter, you will learn: Ø To introduce the array data structure. Ø To understand the use of arrays to store, sort and search lists and tables of values. Ø To understand how to define an array, initialize an array and refer to individual elements of an array. Ø To be able to define and manipulate multiple subscript arrays. 3

4 Introduction Arrays Ø Structures of related data items Ø Static entity – same size throughout program Ø Dynamic data structures 0 1 2 3 4

• Arrays 5 Name of array (Note that all elements of this array have the same name, c) – Group of consecutive memory locations – Same name and type • To refer to an element, specify – Array name – Position number • Format: arrayname[ position number ] – First element at position 0 – n element array named c: c[ 0 ], c[ 1 ]. . . c[ n – 1 ] c[0] c[1] c[2] c[3] c[4] c[5] c[6] c[7] c[8] c[9] c[10] c[11] -45 6 0 72 1543 -89 0 62 -3 1 6453 78 Position number of the element within array c

Arrays Array elements are like normal variables: c[ 0 ] = 3; printf( "%d", c[ 0 ] ); Perform operations in subscript. If x equals 3 c[ 5 - 2 ] == c[ 3 ] == c[x] 6

Defining Arrays • When defining arrays, specify Ø Name Ø Type of array Ø Number of elements array. Type array. Name[ number. Of. Elements ]; Examples: int c[ 10 ]; float my. Array[ 3284 ]; • Defining multiple arrays of same type – Format similar to regular variables Example: int b[ 100 ], x[ 27 ]; 7

Examples Using Arrays 8 • Initializers int n[ 5 ] = { 1, 2, 3, 4, 5 }; – If not enough initializers, rightmost elements become 0 int n[ 5 ] = { 0 } • All elements 0 – If too many a syntax error is produced syntax error – C arrays have no bounds checking • If size omitted, initializers determine it int n[ ] = { 1, 2, 3, 4, 5 }; – 5 initializers, therefore 5 element array

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Examples Using Arrays KIC/Computer Programming & Problem Solving 10

Examples Using Arrays 11

Examples Using Arrays 12

Character Arrays – String “first” is really a static array of characters – Character arrays can be initialized using string literals char string 1[] = "first"; • Null character '' terminates strings • string 1 actually has 6 elements – It is equivalent to char string 1[] = { 'f', 'i', 'r', 's', 't', '' }; – Can access individual characters string 1[ 3 ] is character ‘s’ char string 1 [6]="first"; char string 1 [6]={'f', 'i' , 'r' , 's' , 't' , '' }; char string 1 [ ]={'f', 'i' , 'r' , 's' , 't' , '’}; 13

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Character Arrays – Array name is address of array, so & not needed fo scanf( "%s", string 2 ); • Reads characters until whitespace encountered KIC/Computer Programming & Problem Solving 15

Multiple-Subscripted Arrays • Multiple subscripted arrays – Tables with rows and columns (m by n array) – Like matrices: specify row, then column Column 0 Column 1 Column 2 Column 3 Row 0 Row 1 Row 2 a[ 0 ][ 1 ] a[ 0 ][ 2 ] a[ 0 ][ 3 ] a[ 1 ][ 0 ] a[ 1 ][ 2 ] a[ 1 ][ 3 ] a[ 2 ][ 0 ] a[ 2 ][ 1 ] a[ 2 ][ 3 ] Column subscript Array name Row subscript 16

17 Multiple-Subscripted Arrays • Initialization 1 3 2 4 – int b[ 2 ] = { { 1, 2 }, { 3, 4 } }; – Initializers grouped by row in braces – If not enough, unspecified elements set to zero int b[ 2 ] = { { 1 }, { 3, 4 } }; • Referencing elements – Specify row, then column printf( "%d", b[ 0 ][ 1 ] ); int num[2][2]={{100, 200}, {10, 20}}; 1 3 0 4

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Example of 2 D array location • A[3][4]= {{2, 6, 20}, {2, 2}, {11, 4, 3, 1}} – A[1][2]= 0 – A[2][3]= 1 – A[0][1]= 6 • B[3][]= {{1, 0, 3}, {3, 5, 6}} – B[2][2]=0 – B[0][1]=0 – B[1][2]=6 KIC/Computer Programming & Problem Solving 23

2 D array examples • Write a C code that create a 2 x 2 array. Then let the user to input these elements. • once all values are entered calculate the summation of all elements. KIC/Computer Programming & Problem Solving 24

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2 D array examples • Write a C program to find sum of two matrix of order 2 x 2 using multidimensional arrays where, elements of matrix are entered by user. KIC/Computer Programming & Problem Solving 26

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