What is the difference?

#1

int n;
cin >> n;

What is the differece since both are of size n given by the user as input?

int a[n];

int *a = new int[n];

#2

This means that a is a pointer which is pointing at the starting of the int array index, this is known as dynamic allocation.

a[0] a[1] a[2] a[3] a[4] a[5]
 ^
 |
*a

whereas this means that

a is the array of size n of int data type, this is known as static allocation.(if instead of variable, a fixed value is being provided like a[100] or any other value).

#3

In the case of

we’re taking n as input from user then we dont know what is the size of the array a, Does it considered as static allocation?

#4

No, as the user can enter any digit equal to or less then 100000, so it won’t be static.
If user enters any value of n after compilation of the program, it’s dynamic allocation. Whereas if he enters any value before compilation of a program it’s static.

#5

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