class Example {

    public static void Main() {
        int variable = 0;
        bool success = SomeProcedureWithRef(ref variable);
        // At this point success == true, variable == 10

        // This declaration is ok because after the call outVariable must have been set
        int outVariable;
        bool success = SomeProcedureWithOut(out outVariable);
        // At this point success == false, variable == 20
    }

    public static bool SomeProcedureWithRef(ref int value) {
        value = 10; // This is optional (but often helpful)
        return true;
    }

    public static bool SomeProcedureWithOut(out int value) {
        value = 20; // Compile time error if not setting value
        return false;
    }

}