Can please someone elaborate me this in very brief manner?

Quote:

What will be the difference if i change the value from 0 to 10?

What value? There is no "0"!

Look at the line of code, and break it down:

int *arr=new int[size];

int                        Integers are involved.
int *                      It's a pointer to an intger
int *arr                   The is called "arr" and it holds a pointer to an integer
int *arr=new               We want a new lump of memory allocated at run time.
int *arr=new int           The new memory will be integer(s)
int *arr=new int[...]      The new memory is an array of integers
int *arr=new int[size]

Allocate at run time an array of integers - the contents of size says how many integers the array will hold, and store a pointer to the first element in arr