To calculate compound interest

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C++

/* This program is used to calculate the Compound Interest, given the necessary parameters*/
#include <iostream>
using namespace std;
#include <iomanip>
using std::setw;

int main ()
{
	int principal, rate, time, n, a;  //the Rate should be declared as a float or Double to that it can accommodate decimal values because rate should be in decimal
	cout << "Enter the Principal \n";
	cin >> principal;
	cout << "Enter the Rate \n";
	cin >> rate;
	cout << "Enter the Time \n";
	cin >> time;
	cout << "Enter the Number of Years \n";
	cin >> n;
	a = principal*(1+rate/n)^n*time;
	cout << "The Compound Interest for " << n << " months is " << a << "\n";

	return 0;
}

I get error message "Error: expression must have integral or enum type" from the code above when I try to run it.
I'm trying to write a program that calculate the compound Interest
NB: The problem is in the rate. The data type for the rate should be float or double so that it can accommodate decimal. The code works if I declare all the variables as integers

What I have tried:

I have tried to declare all the variables as float or double but it doesn't work.