using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

// DllImportに必要

using System.Runtime.InteropServices;

namespace C_helloGUI

{

    public partial class Form1 : Form

    {

        //数値の値渡し

        [DllImport("mydll.dll", CallingConvention = CallingConvention.Cdecl)]

        private extern static int add(int a, int b);

        //文字列の参照渡し

        [DllImport("mydll.dll", CallingConvention = CallingConvention.Cdecl)]

        private extern static void test_str(StringBuilder str);

        public Form1()

        {

            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)

        {

            //textBox1.Text = "Hello　World！";

            //追記部分

            int result = add(10, 3);

            Console.WriteLine("dll add = {0}", result);

            StringBuilder buff = new StringBuilder();

            buff.Append("C#からの文字列");

            test_str(buff);

            Console.WriteLine("dll test_str = {0}", buff);

            textBox1.Text = buff.ToString();

        }

    }

}