C#函数out多个返回值问题

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void btn_Test_Click(object sender, EventArgs e)
        {
            //提前声明返回参数变量
            string str;
            int num;
            getValue("测试字符", 6,out str,out num);//调用函数返回数值

            //输出查看
            Console.WriteLine("str:" + str + "；类型：" + str.GetType().ToString());
            Console.WriteLine("num:" + num + "；类型：" + num.GetType().ToString());
        }
        
        //定义测试函数
        public void getValue(string in_str, int in_int, out string out_str, out int out_int)
        {
            out_str = in_str + "+新加字符";
            out_int = in_int + 660;//函数结束一定给所有out对应变量赋值
            
        }
    }

}

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            int c , d ;
            calculate(2, 3, out c,out d);
            Console.WriteLine(c);
            Console.WriteLine(d);
            Console.ReadLine();
            
        }
 
        private static void calculate(int a, int b, out int c, out int d)
 
        {
            c = a + b;
            d = a - b;
 
 
        }
    }
}

        static void Main(string[] args)
        {
            int c;
            if (calculate(2, 3, out c))
                Console.WriteLine("c = "+c);
            else
                Console.WriteLine("Nothing");
            Console.ReadLine();
            
        }
 
        private static bool calculate(int a, int b, out int c)
 
        {
            bool t;
            if (a > b)
                t = true;
            else
                t = false;
            c = a - b;
            return t;
 
        }