Hi friends what’s up? I hope you are well. In last tutorial
we learning about Boolean. Today we will learning about arrays.
An array is a group of like-typed variables that are
referred to by a common name. Arrays of any type can be created and may have one
or more dimensions.
One-Dimensional
Arrays
A
one-dimensional array is, essentially a list of like-typed variables. To create
an array, you first must create an array variable of the desire type. General
form of one-dimensional array declaration is
type var_name[];
For example,
the following declares an array named month_days
with the type “array of int”:
int month_days[];
Although tis
declaration establishes the fact that month_days
is an array variable, no array actually exists. In fact, the value of month_days is set to null, which
represents an array with no value. To link month_days
with an actual, physical array of integers, you must allocate one using new and assign it to month_days. new is a special operator
that allocate memory.
The general
form of new as it applies to
one-dimensional arrays appears as follows:
array_var=new type[size];
This example
allocates a 12-element array of integers and links them to month_days.
month_days = new int[12];
Let’s go to
complete example:
public class Array {
public static void
main(String args[]){
int month_days[];
month_days = new int[12];
month_days[0] = 31;
month_days[1] = 28;
month_days[2] = 31;
month_days[3] = 30;
month_days[4] = 31;
month_days[5] = 30;
month_days[6] = 31;
month_days[7] = 31;
month_days[8] = 30;
month_days[9] = 31;
month_days[10] = 30;
month_days[11] = 31;
System.out.println("April
has " + month_days[3] + " days.");
}
}
I hope you now understand array. But still you do not see the advantage
of array. Think we have to take ten input…….
import java.util.Scanner;
public class teninput {
public static void
main(String args[]){
Scanner pavel = new Scanner(System.in);
int mostafij[] = new int[10];
int total = 0;
for(int i=0;i<10;i++){
System.out.println("Enter
an ineger number ");
mostafij[i] = pavel.nextInt();
total = total+mostafij[i];
}
int avarage = total/10;
System.out.println("Avarage
of these number is " + avarage);
}
}
Now I hope you are able to find the advantage of arrays. Advantage you
will take many number and out many number in a easy way by using arrays.
Multidimensional Arrays
In java multidimensional
arrays are actually arrays of arrays. These, as you might expect, look and act
like regular multidimensional arrays. However, as you will see, there are a
couple of subtle differences. To declare a multidimensional array variable,
specify each additional index using another set of square brackets. For example,
the following declares a two-dimensional array variable called twoD.
int twoD[][]
= new int[4][5];
This allocates a 4 by 5
array and assigns it to twoD. Internally this matrix is implemented as array of
array of int.
Here a example:
public class towD {
public static void
main(String args[]){
int TowD[][] = new int[4][5];
int i,j,k=0;
for(i=0;i<4;i++){
for(j=0;j<5;j++){
TowD[i][j] = k;
k++;
}
}
for(i=0;i<4;i++){
for(j=0;j<5;j++){
System.out.printf(TowD[i][j]
+ "\t");
}
System.out.println();
}
}
}
Output:
0 1 2 3 4
5 6 7 8 9
10 11 12 13 14
15 16 17 18 19
0 comments:
Post a Comment