C# out parameter in extension method

Question

In an extension method, I am receiving an error that my 'out' parameter does not exist in the current context. I assume this means that extension methods cannot have 'out' parameters, but this is not specified in the documentation. I would appreciate it if someone could please clarify!

public static int customMax(this int[] data, out index)
{
    int max = data[0];
    index = 0;

    for (int i = 1; i < data.Length; i++) {
        if (data[i] > max) {
            max = data[i];
        }
    }

    return max;
}

Answer 1

Extension methods can have out parameters. You need to specify the type of your out parameter. So change code

public static int customMax(this int[] data, out index)

to

public static int customMax(this int[] data, out int index)

and it should all work