pointer typecasting

#include<stdio.h>
#include<stdlib.h>
int main()
{
	int n;
	int aj;
	int aj2;
	int bj;
	printf("Enter size of array\n");
	scanf_s("%d", &n);
	int *A = (int*)malloc(n*sizeof(int));//dynamically allocated array
	for (int j = 0; j < n; j++)
	{
		aj2 = j + 1;
		A[j] = j + 1;
		aj = A[j];
	}
	//free(A);
	//A[1] = 3; //value at address A+1;
	int *B = (int*)realloc(NULL, n*sizeof(int)); //equivalent to malloc
	printf("Prev block address=%d, new address=%d difference=%d\n", A, B,(B-A));
	for (int j = 0; j < n; j++)
	{
		bj = B[j];
		printf("%d ", B[j]);
	}
}

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I am doing self study, copying code from tutorial.

      int *B = (int*)realloc(NULL, n*sizeof(int)); //equivalent to malloc
I do not undertand (int*) typcasting
would (int) force a number where there is a decimal
4.01=4
I do not undertand (int*)