Chapter 9 Array

YAW- credit to HAA,RAK & AIH1

CHAPTER 9: Array

BEE1222: COMPUTER PROGRAMMING


Syllabus

• Array Initialization9.1

• Passing Array to Function9.2

• Multidimensional Array9.3


Lesson Outcomes

1. Understand the concept of array and able to

use it to minimize the complexity of the program

2. Understand the concept of multidimensional

array


How programmer needs to keep track a

number of UMP

students ???

Array : Easy for memory allocation and saving data

Database(store/sort/

search/tables of value)

9.1 Array Initialization


Arrays Collection of data elements which hold

multiple variables of the same data type.

An index is used to identify the elements of the array.

In C, indexing starts at zero

Programmer can put in any type of data in the defined array memory such as integer, floating point, character etc.


Using Arrays Array data type can be used in all elements of

programming:1. I/O Statements2. Operation Statements3. Selection Statement4. Repetitive Statements5. Functions


Array Types Single array a[n] multidimensional array a[n][m] String array – char a[n]


Name of array a[0]

a[1]

a[2]

a[3]

a[4]

a[5]

a[6]

a[7]

a[8]

a[9]

a[10]

0

1

2

3

4

5

6

7

8

9

Value in memory location

Example of memory allocation for 10-elements array


Syntax:

Data_type variable_name [elements];

char ch [10];

int a [5];

int b[3], c[7];

Array (Declaration)


Array (Initialization)

data_type a[n] = {d0,d1……,dn-1};

int a[5] = {0,1,2,3,4}; example: a[4] = 3

double x[3]= {5.5,4.4,3.3};

char vowel [5]={‘a’,‘e’,‘i’,‘o’,‘u’}; char vowel [5]=“aeiou”;

Data_type variable_name [elements] = {value_list};

For holding strings

int names[2];names[0] = 101;names[1] = 232;


Example 1

#include <stdio.h>

int main ( ){ int a[6] = {1, 2, 223, 56, 889, 90}, i; for(i=0;i<=5;i++) { printf ("%d\t",a[i]); }

return(0);}


Example 2 #include <stdio.h>

int main (){

int n[10],i;

for (i=0;i<10;i++){n[i]=0; //initialize array}printf ("%s%13s\n", "Element","Value");

for (i=0;i<10;i++) //print array{printf("%7d %13d\n", i ,n[i]);}

return 0;}


Example 3#include <stdio.h>#include <conio.h>#define SIZE 10int main (){

int i, n[SIZE];printf ("Insert 10 value of n =");for (i=0;i<=9;i=i+1){

scanf ("%d", &n[i]);}printf ("Your entered values are :\n");for (i=0;i<=9;i=i+1) //print array{

printf("\tn[%d]=%d\n", i ,n[i]);}

getch ();return 0;}


9.2 Passing Array to Function The array is passed

as an array of unspecified size (int array[])OR

as a pointer (int *arrayPtr) Changes to the array within the function

affect the “original” array


Example 4 #include <stdio.h>#include <conio.h>

int addNumbers(int fiveNumbers[]); /* declare function */

int main() { int array[5]; int i; printf("Enter 5 integers separated by spaces: "); for(i=0 ; i<=5 ; i++)

{ scanf("%d", &array[i]); }

printf("\nTheir sum is: %d\n", addNumbers(array)); getch (); return 0;}

int addNumbers(int fiveNumbers[]) /* define function */{ int sum = 0; int i; for(i=0 ; i<=5 ; i++)

{ sum+=fiveNumbers[i]; /* work out the total */ } return sum; /* return the total */}


9.3 Multi Dimensioned Arrays have two or more index values which specify the

element in the array.

Declaration & Calculation :

int m1[10][10];

int m2[2][2] = { {0,1}, {2,3} };

sum = m1[i][j] + m2[k][l];

row Colum

n


Multi Dimensioned ArraysValue in memory location

a[0][m]

a[1][m]

a[2][m]

a[3][m]

A

33

0

22

30

5

7

7 7

8

9

4

4

4

4

a[n][0] a[n][1] a[n][2] a[n][2]

n = 0,1,2,3

m = 0,1,2,3


Example 5#include <stdio.h>#include <conio.h>

int main(){

int m[4][3] = { {10,5,-3}, {9, 0, 0}, {32,20,1}, {0,0,8} };

int row, column, sum;

sum = 0;for( row = 0; row < 4; row++ )

for( column = 0; column < 3; column++ )sum = sum + m[row][column];

printf("The total is %d\n", sum );

getch (); return 0;

}


Example 6 :Passing Arrays to Functions#include <stdio.h>

#include <conio.h>

void printArray(int array[][4]); /* declare function */

int main() {

int array[3][4] = {0,1,2,3,4,5,6,7,8,9,10,11};

printArray(array);

getch ();

return 0;

}

void printArray(int array[][4]) { /* define function */

int i, j;

for(i=0 ; i<3 ; i++) {

for(j=0 ; j<4 ; j++) {

printf("%2d ", array[i][j]);

}

printf("\n");

}

}


Character Data Type

Declaration & initialization of character variable char identifier_name;

char identifier_name = „char_literal‟;

Identifier_name = „char_literal‟;

Accept single character of alphanumeric orsymbols (including blank).


Character Input and Output

Character input

scanf(“ %c”, &ch)

Note: A space included before %c

type specifier

Character output

printf(“%c”, ch)


Operations on Character Type

Operation

Copy ch1 = ch2

Logical operators ==/!=

<, <=, >=, >

Increment/decrement

Character manipulation

#include <ctype.h>

Example isalpha()

islower()

isupper()

isdigit()

isspace()

tolower()

toupper()


String

Character array (array of char data type)

Declaration & initialization of string variable char str[str_len];

char str[] =

“strings_value”;

Note: string will add null character \0 to mark end ofstring causing number of character storedalways one less than str_len


String Input and Output

String Input

scanf(“%ms”, str);

gets(str);

Note: Ampersand (&) not included

as prefix to string variableidentifier

Input Text longer than stringlength will cause overflow ofstring variable

String Output

printf(“%-s”,str);

puts(str);

Note: Adding minus (-) sign to

type specifier (s) cause leftjustification of string

String variable without nullcharacter (\0) may causerun-time error


Operation with String

String library function #include <string.h>,<stdlib.h>

String initialization or assignment statement strcpy(str_var, “str_text”);

Checking length of string variable to avoidoverflow

strlen(str_var);


Using Strings with Functions

Sting is array of character, therefore using stringdata type with function is similar to using

numeric array with function discussed in earliertopic.


Array of String

Two-dimensional array of character type

Declaration char str_ary[row][col];

char str_ary[row][col] = {“str1”,“str2”, …, str_row};


Example 7

Compile result:My Name is Siti

#include <stdio.h>#include <string.h>

int main ( ){char *name;strcpy(name,"Siti");printf("My Name is %s\n",name);strlen("Siti");return(0);}


Example 8#include <stdio.h>#include <stdlib.h>#include <conio.h>int main ( ){char string1[20];char string2[ ]="String literal";int i;

printf("Enter a string: ");scanf("%s", string1);

printf("String1 is: %s\nString2 is: %s\n" "String1 with spaces between characters is: \n", string1,string2);

for (i=0;string1[i]!= '\0';i++){ printf("%c", string1[i]);}

printf("\n");

return (0);}


Example 9#include <stdio.h>#include <stdlib.h>#include <conio.h>Int main ( ){char *string1;int *array_of_nums;int str_siz, num_nums, i;

printf("Enter string length and string = ");scanf("%d", &str_siz);

string1 = (char*)calloc(str_siz,sizeof(char));scanf("%s",string1);printf("\nHow many numbers?\n");scanf("%d",&num_nums);

array_of_nums = (int*)calloc(num_nums, sizeof(int));array_of_nums[0] = 5;

for(i = 1; i <num_nums; ++i){array_of_nums[i] = array_of_nums[i-1]*i;}return (0);}

Compile result:Enter string length and string = 9 alyanHow many numbers4


Illustration:

Compile result:Enter string length and string = 9 alyanHow many numbers4

String1

Array_of_nums

5

5

10

30

a l y a n \0 \0 \0 \0


END OF CHAPTER 91. Q& A2. Outcomes

Understand the concept of array and able to use it to

minimize the complexity of the program

Understand the concept of multidimensional array

3. Reflection

Documents

Chapter 9 Array