extern外部方法使用C#的实现方法

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;//引用外部
 
namespace extern
{
    public partial class DllImportForm : Form
    {
        public DllImportForm()
        {
            InitializeComponent();
        }
 
        [DllImport("kernel32", SetLastError = true)]//声明和实现的连接
        public static extern int GetCurrentDirectory(int a, StringBuilder b);//外部方法
       
        private void btnDisplay_Click(object sender, EventArgs e)
        {
            StringBuilder pathstring=new StringBuilder ();//返回路径
            GetCurrentDirectory(300, pathstring);
           this.listBox1.Items.Add (pathstring );
 
        }
    }
}