F2037 - PROGRAMMING
FUNDAMENTAL WITH C++
Unit 4.1 - Understand the use of array

INDEX
 Objective
 Introduction to Array
 One dimensional array
 Two dimensional array

OBJECTIVES
 At the end of this module, students should be
able to:
 Declare and use an array
 Use the array statement in C++ program
 Accessing element in an array

ARRAY DEFINITION
 Array is a collection of data elements of the
same type that are referenced by a common
name.
 Used to process a collection of data all of which is
of the same type, such as list of name, list of
temperature.

ARRAY DEFINITION
 Array’s element consist of memory allocation and
identified by index.
 Array size : 9
1st Index Indexs
0 1 2 3 4 5 6 7 8

 Two types of arrays
 One-dimensional array
 Two-dimensional array

DECLARING ONE DIMENSIONAL
ARRAY
 Will have a single row and can have any number
of columns.
 Will have only one subscript. Subscript refers to
the dimension of the array.
 Array declaration of 10 alphabet
 type array_name[size]
 Eg : char huruf[10];

INITIALIZING ONE DIMENSIONAL
ARRAY
 Initialization is the process of assigning values to
the array you have created.
 To assign initial values to each one of array’s
elements we must enclose the values in curly
braces ({ }) and separate them with comma (,).
 Eg : char huruf[5] = {‘a’, ‘b’, ‘c’, ‘d’, ‘e’};

INITIALIZING ONE DIMENSIONAL
ARRAY
 Eg: int nombor[3] = {3, 24, 31};
first index 0 1 2
nombor 3 24 31
nombor[0];//3
nombor[1];//24
nombor[2];//31
nombor[0+1];//nombor[1];//24
nombor[3];

ACCESSING ELEMENT OF ONE
DIMENSIONAL ARRAY
 Element is accessed by its index
 Array index refers to the location of the values in an
array.
 The first element will always have the array index as
0.
Syntax :
<Variable name>[Array index] = Value;
For example:
marks[0]=95;
marks[1]=85;
marks[2]=75;

ACCESSING ELEMENT OF ONE
DIMENSIONAL ARRAY
 Eg:
int my_array[5] = {11, 22, 33, 44, 55};
 to store the value 75 in the third element
of my_array, we could write the following
statement:
my_array[2] = 75;
 to pass the value in 4th element of my_array and
store the value into temporary variable,
temp_value:
int temp_value = my_array[3]; // also
equals to 44

ACCESSING ELEMENT OF ONE
DIMENSIONAL ARRAY
 if the name of an array is name, then name[0] is
the name of the element that is in position 0,
name[1] is the name of the element that is in
position 1, etc.
 in general, the nth element is in position n-1. So
if the array has n elements, their names are
name[0], name[1], name[2], …, name[n-
1].
 it is important to be able to clearly distinguish
between the two uses that brackets [ ] have
related to arrays:
int name[5]; // declaration of a new array
name[2] = 75; // access to an element of the
array.

EXAMPLE
 Program Student_Marks.cpp will illustrate how
to declare an array, initialize and access its
elements.

#include<iostream>
using namespace std;
void main()
{ marks[0] : 95
int marks[]={95,85,75,80,65}; marks[1] : 85
cout<<"marks[0] : "<<marks[0]; marks[2] : 75
marks[3] : 80
cout<<"nmarks[1] : "<<marks[1];
marks[4] : 65
cout<<"nmarks[2] : "<<marks[2];
cout<<"nmarks[3] : "<<marks[3];
cout<<"nmarks[4] : "<<marks[4];
}

EXAMPLE
 Program Onedim_Int_Array.cpp illustrates how
to initialize integer array and display its
contents.

#include<iostream>
using namespace std;
void main()
{
int y[4]={8,7,6,4};
for(int i=0;i<4;i++)
{
cout<<y[i]<<"n";
}
}

EXAMPLE
 Program Onedim_Char_Array_Name.cpp
illustrates how to initialize a character array and
display its contents.

#include<iostream>
using namespace std;
void main()
{
char stud_name[]={‘M',‘A',‘F','I','A'};
for(int i=0;i<=4;i++)
{
cout<<stud_name[i];
}
}

ENTERING DATA INTO AN ARRAY
 When more number of values are to be stored
in an array, a for loop can be used.
 The sample code shows how to use a for loop
in an array.
for(int i=0;i<5;i++)
{
cout<<“Enter the marks: ";
cin>>marks[i];
}

READING DATA FROM AN ARRAY
 You can use a for loop with a single cout
statement to print the values from an array.
for (int i=0;i<5;i++)
{
cout<<"Marks : "+marks[i]);
}

EXAMPLE
 Program One_Int_Array.cpp illustrates how to
accept five marks from the user and prints the
values on the screen.

#include <iostream>
using namespace std;
void main()
{
int marks[5];
//Accepting the marks
for(int i=0;i<5;i++){
cout<<"Enter mark :";
cin>>marks[i];
}
cout<<"nThe marks you have enter is"<<endl;
//Displaying the array
for(int i=0;i<5;i++){
cout<<"Marks:"<<marks[i]<<endl;
}
}

IN CLASS EXERCISE 4.1
 Declare an array alpha of 15 elements of type
int.
 Access the value of tenth element of array alpha.
 Set the value of fifth element of array alpha to
35.
 Set the value of ninth element of array alpha to
the sum of fifth and sixth element of array
alpha.

 Declare an array alpha of 15 elements of type
int.
int alpha [15];
 Access the value of tenth element of array alpha.
alpha [9];
 Set the value of fifth element of array alpha to
35.
alpha [4] = 35;

 Set the value of ninth element of array alpha to
the sum of fifth and sixth element of array
alpha.
alpha [8] = alpha [4] + alpha [5]

 What is the output
#include<iostream>
using namespace std;
void main()
{
double num []= {2.0, 4.0, 6.5, 8.7};
cout<<num[1+2];
}

 How to fill in value into array  Output:
//program output
#include <iostream> 1
using namespace std; 2
void main() 3
{ 4
for(int i = 0; i < 10; ++i) 5
{ 6
cout << i+1 << “n";
7
}
8
}
9
10

#include <iostream>
using namespace std;
void main()
{
int num[]={1,2,3,4,5,6,7,8,9,10};
for(int i = 0; i < 10; ++i)
{
cout << num[i]<< "n";
}
}

TWO-DIMENSIONAL ARRAY
 Two-dimensional arrays can be described as
"arrays of arrays".
 For example, a two-dimensional array can be
imagined as a two-dimensional table made of
elements of a same uniform data type.

PRESENTATION OF TWO-
DIMENSIONAL ARRAY

 Assume that there are 5 students in a class and
each of them study three different subjects, for
example Mathematics, Physics and Chemistry.

Example
int marks_table [5][3];
Syntax
<Data type> <Variable name> [Row][Column];

TWO-DIMENSIONAL ARRAY
 Table jimmy represents a bidimensional array of
3 by 5 elements of type int.
 The way to declare this array in C++ would be:
int jimmy [3][5];
column
row

INITIALIZING TWO-DIMENSIONAL
ARRAY
 Eg:
 int array1[ 2 ][ 3 ] = { { 1, 2, 3 }, { 4, 5, 6 } };
 Output:
123
456
 int array2[ 2 ][ 3 ] = { 1, 2, 3, 4, 5 };
 Output:
123
450
 int array3[ 2 ][ 3 ] = { { 1, 2 }, { 4 } };
 Output:
120
400

ACCESSING ELEMENT IN TWO-
DIMENSIONAL ARRAY
 Element is accessed by the index of its row and
column.
 Eg:
 Toaccess the element in the 2nd row and at the 4th
column of this two-dimentional array, we can used
the following code:
jimmy[1][3];

#include<iostream>
using namespace std;
void main()
{
int array2[ 2 ][ 3 ] = {{ 1, 2, 3} ,{4, 5,6 }};
for(int index1=0;index1<2;index1++)
{
for(int index2=0;index2<3;index2++)
cout<<array2[index1][index2] << " ";
cout<<endl;
}
}

OUTPUT

WHAT IS OUTPUT?
#include<iostream>
using namespace std;
void main()
{
int marks_table[5][3] = {{83,99,74},
{88,90,72},{89,88,82},
{98,93,75},{78,60,65}};
cout<<marks_table[1][2];
}

#include<iostream>
#include<string>
using namespace std;
void main()
{
string Data [2][3];
//For first fow
Data[0][0] = "Lisa"; //lastname
Data[0][1] = "Sulaiman"; //firstname
Data[0][2] = "Kedah"; //location
//Second row
Data[1][0] = "Ali"; //lastname
Data[1][1] = "Muhammad"; //firstname
Data[1][2] = "Johor"; //location
cout<<"LastnametFirstnametLocationn";
for(int i=0;i<2;i++){
for(int j=0;j<3;j++){
cout<<Data[i][j]<<"tt";
}
cout<<"n";//move to new line
}
}

#include <iostream>
using namespace std;
void main()
{
int array2[ 23 ][ 4 ];
//Accepting the marks
for (int row=0; row<2; row++) {
for(int col=0; col<3; col++){
cout<<"Enter mark ["<<(row)<<"][" <<col <<"]: ";
cin>>array2[row][col];
}
cout<<endl;
}
//display
for(int row=0; row<2; row++){
for(int col=0; col<3; col++)
cout<<array2[row][col] << " ";
cout<<endl;
}
}

OUTPUT

IN CLASS EXERCISE 4.2
 Declare an array beta of 10 rows and 20 columns
of type int.
 Examine the following:
double values[ ] [ ] = {
{1.2, 9.0, 3.2},
{9.2, 0.5, 1.5},
{7.3, 7.9, 4.8} } ;
What is the value of values[2][1]?

 Which of the following statements constructs
an array with 5 rows of 7 columns?
long stuff[5][7];
long[5][7];
long stuff[7][5];
long [7][5];

 Declare an array beta of 10 rows and 20 columns
of type int.
int beta [10][20]
o Value of values[2][1]? 7.9
o long stuff[5][7];

SUMMARY
 An array is a structured data type with a fixed
number of elements.
 Every element of an array is of the same type
and can be accessed by their index.
 Array index started with 0.
 Array can be initialized during declaration.
 A one-dimensional array has one subscript.
 In two-dimensional array, elements are arranged
in table form.
 To access element from two-dimensional array,
pair of indices is needed (index for row and index
for column).