I'm receiving this error when I'm trying to run my program: Program received signal: “EXC_BAD_ACCESS”.
Does anyone know what this means?

Can you show the line of code that throws the exception?

This is the code I have written so far. Right now the code only gets the polynomial, later it will create the derivative. The error is not in the code itself. It runs until all the coefficients are input and then I get the bad access thing.

#include <iostream>
#include <cmath>

using namespace std;

double poly(double[], int);
double drv(double[], int, double);

int main ()
{
	int n;
	cout << "Enter the degrees of the polynomial: ";
	cin >> n;
	
	double c[n];
	
	for (int i=n; i>=0; i--) 
	{
		cout << "Enter the coefficient for the variable of degree " << i << ": ";
		cin >> c[i];
	}
    
	cout << "The polynomial entered is: " << poly(c,n) << endl; //I think this is where it's messing up
	
	return 0;
}

double poly(double c[], int n)
{
	double sum=0.0;
	double x;
	
	for (int i=0; i<=n; i--) 
	{
		sum+=c[i]*pow(x, i);
	}
	
	return sum;
}

Does your compiler compile this?
You are allocating an array with a non-constant (line 15)

Also x is never initialized and is used on line 35.

What does this mean?

You are allocating an array with a non-constant (line 15)

The compiler compiles it until it reaches the point where it's supposed to pick up from the function, so something is wrong with the function. The x is because I want it to say that it's the coefficient (c) times x^i, because later on in the program I need it to take the derivative.

x does not have a value.
You will get random results at best or a crash.

How could I do it differently?

If your intention is to use the pow() function, both parameters need to have actual values.
...meaning: The variable x needs a value before you use it.