FP201 - PROGRAMMING FUNDAMENTALS Unit Understand the use of array PREPARED BY: MAZNAH AHMAD, JTMK PSIS

I NDEX Objective Introduction to Array One dimensional array Two dimensional array

O BJECTIVES 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

A RRAY D EFINITION 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.

A RRAY D EFINITION Array’s element consist of memory allocation and identified by index. Array size : st Index Indexs

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

D ECLARING O NE D IMENSIONAL A RRAY 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];

I NITIALIZING O NE D IMENSIONAL A RRAY 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’};

I NITIALIZING O NE D IMENSIONAL A RRAY Eg: int nombor[3] = {3, 24, 31}; nombor[0];//3 nombor[1];//24 nombor[2];//31 nombor[0+1];//nombor[1];//24 nombor[3]; nombor first index

A CCESSING E LEMENT OF O NE D IMENSIONAL A RRAY  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 : [Array index] = Value; For example: marks[0]=95; marks[1]=85; marks[2]=75;

A CCESSING E LEMENT OF O NE D IMENSIONAL A RRAY  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 4 th element of my_array and store the value into temporary variable, temp_value : int temp_value = my_array[3]; // also equals to 44

A CCESSING E LEMENT OF O NE D IMENSIONAL A RRAY  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.

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

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

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

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

E XAMPLE Program Onedim_Char_Array_Name.cpp illustrates how to initialize a character array and display its contents.

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

E NTERING D ATA INTO AN A RRAY  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]; }

R EADING D ATA FROM AN A RRAY 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]); }

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

#include 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; }

I N C LASS E XERCISE 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 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 #include using namespace std; void main() { for(int i = 0; i < 10; ++i) { cout << i+1 << “\n"; }  Output: //program output

#include 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-D IMENSIONAL A RRAY 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.

P RESENTATION 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 [Row][Column];

TWO-D IMENSIONAL A RRAY 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]; row column

I NITIALIZING TWO-D IMENSIONAL A RRAY Eg: int array1[ 2 ][ 3 ] = { { 1, 2, 3 }, { 4, 5, 6 } }; Output: int array2[ 2 ][ 3 ] = { 1, 2, 3, 4, 5 }; Output: int array3[ 2 ][ 3 ] = { { 1, 2 }, { 4 } }; Output:

A CCESSING E LEMENT IN TWO-D IMENSIONAL A RRAY Element is accessed by the index of its row and column. Eg: To access the element in the 2 nd row and at the 4 th column of this two-dimentional array, we can used the following code: jimmy[1][3];

#include 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; }

O UTPUT

W HAT IS OUTPUT ? #include 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 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<<"Lastname\tFirstname\tLocation\n"; for(int i=0;i<2;i++){ for(int j=0;j<3;j++){ cout<<Data[i][j]<<"\t\t"; } cout<<"\n";//move to new line }

#include 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; }

O UTPUT

I N C LASS E XERCISE 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];

S UMMARY 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).