how to reallocate memory in c++?

Question

int *a;
a = new int[5];
a[0] = 5;
cout<< a << " " << a[0] << endl;
a = new int[10];
cout<< a << " " <<a[0];

In the above code both the output of a and a[0] are different for both of the outputs.

In C, we use realloc function to dynamically reallocate memory.

As I used new int[10] second time it didn't reallocate memory, it allocates memory in different location instead.