Cannot convert argument 1 from 'float' to 'float[]'

#include <iostream>
using namespace std;

float func(float a[]);

int main()
{
    float x[3] = { 1.5, 2.5, 3.5 };

    *cout << func(x) << endl;*
}

float func(float a[])
{
    float sum = 0;
    for (int i = 0; i < 2; i++)
        sum += a[i];
    return sum;
}