How to write and implement your own function

Question

I need to write my own sqrt function: double my_sqrt_1(double n) How would I go about doing this? At first I tried putting this outside of "int main()":

double my_sqrt_1(double n)
{
    int x = 1;
    x = (x + n / x) / 2;
}

I then put this:

int main()
{
    cout << "Please enter a value ";
    cin >> my_sqrt_1;
    cout << '\n' << x;
}

I also tried:

int main()
{
    cout << "Please enter a value ";
    cin >> my_sqrt_1;
    cout << '\n' << my_sqrt_1;
}

None of this worked though. I'm probably doing this completely wrong, but it made sense in my head.

Answer 1

"I'm probably doing this completely wrong ..."

Sorry to say that, but yes.

You need a variable to receive input, and call your function passing that variable

int main() {
    cout << "Please enter a value ";
    double myNumber;
    cin >> myNumber;
    cout << '\n' << my_sqrt1(myNumber) << endl;
}

Also your function is supposed to return the result of the calculation

double my_sqrt_1(double n) {
    double x = 1.0;
 // ^^^^^^      ^^
    x = (x + n / x) / 2.0;
                    // ^^
    return x; // <<<<<<<<<<<<<<
}