Can anyone explain the arrays ?

Answer 1

On the learn tab at the top of the screen there is a search bar. Enter the term Array here. You should find what you need.

Example of a search result:

https://www.sololearn.com/learn/Java/2148/?ref=app

Answer 2

To store the roll no. of a student, we need to store it in a variable:

int rn;
cout<<"Enter student's roll no";
cin>>rn; //user input

Imagine if you've to store the roll no of 10 students, this will be long job if you do this way:

int rn1, rn2, rn3, rn4, rn5, rn6, rn7, rn8, rn9, rn10;

cout<"Enter roll no of 1st student;
cin>>rn1;
cout<<"Enter roll no of 2nd student;
cin>>rn2;
cout<<"Enter roll no of 3rd student";
cin>>rn3;

...and so on till 10th variable.

Therefore, we have arrays, which is basically a variable which can store more than one values. Like this:

int arr[10]; //size is ten bcoz we need to store ten roll no.s

cout<<"Enter roll number of 10 students";
for(int i=0; i<10; i++)
cin>>rn[i];. //loop will run 10 times