How to open Excel FIles

Question

I am a novice
When I open excel file  I found some problems.
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.Reflection;
using System.Windows.Forms;
using XLS=Microsoft.Office.Interop.Excel;
using WD=Microsoft.Office.Interop.Word;
using Microsoft.Office.Core;
namespace ExcelDataFillWord
    public partial class Form1 : Form
        public Form1()
            InitializeComponent();
        private void button1_Click(object sender, EventArgs e)
            //  Scheduler sched = new Scheduler();
            //foreach (Task t in sched.Tasks)
            //    Console.WriteLine(t.ToString());
            //    foreach (Trigger tr in t.Triggers)
            //        Console.WriteLine(tr.ToString());
        private void label1_Click(object sender, EventArgs e)
            FileDialog.Filter = "excel文件|*.xls|Excel文件|*.xlsx";
            FileDialog.Multiselect = false;
            FileDialog.Title = "打开excel文件";
            if (FileDialog.ShowDialog() == DialogResult.OK)
                textBox1.Text = FileDialog.FileName;
                object missing = System.Reflection.Missing.Value;
                //object missing = Type.Missing;
                CloseProcess();
               //'Excel::Application excel =new Excel::ApplicationClass();
                Microsoft.Office.Interop.Excel.Application excel= new Microsoft.Office.Interop.Excel.Application();
                //Excel::Workbook  Wk =(Excel::Workbook )Xls.Workbooks.Open(textBox1.Text, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing,
missing, missing, missing, missing);
                Microsoft.Office.Interop.Excel.Workbook workbook =(Microsoft.Office.Interop.Excel.Workbook) excel.Application.Workbooks.Open(textBox1.Text , missing, missing, missing,
missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing);
                //comboBox1.Items.Clear();
                //foreach (Excel::Worksheet Sh in Wk.Worksheets)
                //    comboBox1.Items.Add((Sh.Name).ToString());
                workbook.Close(missing, missing, missing);
                excel.Quit();
        private void CloseProcess()
            System.Diagnostics.Process[] excelProcess = System.Diagnostics.Process.GetProcessesByName("EXCEL");//实例化进程对象
            foreach (System.Diagnostics.Process p in excelProcess)
                p.Kill();//关闭进程
            System.Threading.Thread.Sleep(10);//使线程休眠10毫秒
problem is : can't change  excel.applicaitonclass's Com object   to   interface
so I want to ask a question:
excel.application is a interface ,then interface variant = a class( it inherients this interface)  object
but interface is a abstract object ,It has no construct function . why We use  Excel.Applcation xsl=new Excel.Application();

Answer 1

Hello,
Perhaps this will help. Open an Excel file, select a sheet, range then set a value, save then close. The idea here is not to write or save but demo a few basic operations.
Also note 'as is' all memory is cleaned up without resorting to what many do, force the garbage collector. This is important if objects are not cleaned up it is very possible in extreme cases to bring a machine down so one should ensure all objects are cleaned
up which only comes from well written code be it C# or VB.NET
using System;
using System.Data;
using System.Data.OleDb;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using Excel = Microsoft.Office.Interop.Excel;
namespace Example_C1
public partial class Form1 : Form
public Form1()
InitializeComponent();
public void OpenExcelExample(string FileName, string SheetName)
if (System.IO.File.Exists(FileName))
bool Proceed = false;
Excel.Application xlApp = null;
Excel.Workbooks xlWorkBooks = null;
Excel.Workbook xlWorkBook = null;
Excel.Worksheet xlWorkSheet = null;
Excel.Sheets xlWorkSheets = null;
Excel.Range xlCells = null;
xlApp = new Excel.Application();
xlApp.DisplayAlerts = false;
xlWorkBooks = xlApp.Workbooks;
xlWorkBook = xlWorkBooks.Open(FileName);
xlApp.Visible = false;
xlWorkSheets = xlWorkBook.Sheets;
for (int x = 1; x <= xlWorkSheets.Count; x++)
xlWorkSheet = (Excel.Worksheet)xlWorkSheets.get_Item(x);
if (xlWorkSheet.Name == SheetName)
Proceed = true;
break;
System.Runtime.InteropServices.Marshal.FinalReleaseComObject(xlWorkSheet);
xlWorkSheet = null;
if (Proceed)
Excel.Range xlRange1 = null;
xlRange1 = xlWorkSheet.get_Range("A1");
xlRange1.Value = "Hello";
Marshal.FinalReleaseComObject(xlRange1);
xlRange1 = null;
xlWorkSheet.SaveAs(FileName);
else
MessageBox.Show(SheetName + " not found.");
xlWorkBook.Close();
xlApp.UserControl = true;
xlApp.Quit();
ReleaseComObject(xlCells);
ReleaseComObject(xlWorkSheets);
ReleaseComObject(xlWorkSheet);
ReleaseComObject(xlWorkBook);
ReleaseComObject(xlWorkBooks);
ReleaseComObject(xlApp);
MessageBox.Show("Done");
else
MessageBox.Show("'" + FileName + "' not located. Try one of the write examples first.");
private void ReleaseComObject(object obj)
try
System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
obj = null;
catch (Exception)
obj = null;
private void button1_Click(object sender, EventArgs e)
OpenExcelExample(System.IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "WS1.xlsx"), "Sheet3");
private void releaseObject(object obj)
try
if (obj == null)
System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
obj = null;
catch (Exception ex)
obj = null;
MessageBox.Show("Exception Occured while releasing object " + ex.ToString());
finally
GC.Collect();
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