How to open an Excel file in C#?

I am trying to convert some VBA code to C#. I am new to C#. Currently I am trying to open an Excel file from a folder and if it does not exist then create it. I am trying something like the following. How can I make it work?

Excel.Application objexcel;
Excel.Workbook wbexcel;
bool wbexists;
Excel.Worksheet objsht;
Excel.Range objrange;

objexcel = new Excel.Application();
if (Directory("C:\\csharp\\error report1.xls") = "")
{
    wbexcel.NewSheet();
}

else
{
    wbexcel.Open("C:\\csharp\\error report1.xls");
    objsht = ("sheet1");
}
objsht.Activate();

You need to have installed Microsoft Visual Studio Tools for Office (VSTO).

VSTO can be selected in the Visual Studio installer under Workloads > Web & Cloud > Office/SharePoint Development.

After that create a generic .NET project and add a reference to Microsoft.Office.Interop.Excel via 'Add Reference... > Assemblies' dialog.

Application excel = new Application();
Workbook wb = excel.Workbooks.Open(path);

Missing.Value is a special reflection struct for unnecessary parameters replacement

---

In newer versions, the assembly reference required is called Microsoft Excel 16.0 Object Library. If you do not have the latest version installed you might have Microsoft Excel 15.0 Object Library, or an older version, but it is the same process to include.

FileInfo fi = new FileInfo("C:\\test\\report.xlsx");
if(fi.Exists)
{
    System.Diagnostics.Process.Start(@"C:\test\report.xlsx");
}
else
{
    //file doesn't exist
}

private void btnChoose2_Click(object sender, EventArgs e)
{
  OpenFileDialog openfileDialog1 = new OpenFileDialog();
  if (openfileDialog1.ShowDialog() == System.Windows.Forms.DialogResult.OK)
  {
    this.btnChoose2.Text = openfileDialog1.FileName;
    String filename = DialogResult.ToString();
            
    var excelApp = new Excel.Application();
    excelApp.Visible = true;
    excelApp.Workbooks.Open(btnChoose2.Text);
  }
}

Imports

 using Excel= Microsoft.Office.Interop.Excel;
 using Microsoft.VisualStudio.Tools.Applications.Runtime;

Here is the code to open an excel sheet using C#.

    Microsoft.Office.Interop.Excel.Application excel = new Microsoft.Office.Interop.Excel.Application();
    Microsoft.Office.Interop.Excel.Workbook wbv = excel.Workbooks.Open("C:\\YourExcelSheet.xlsx");
    Microsoft.Office.Interop.Excel.Worksheet wx = excel.ActiveSheet as Microsoft.Office.Interop.Excel.Worksheet;
    
    wbv.Close(true, Type.Missing, Type.Missing);
    excel.Quit();

Here is a video mate on how to open an excel worksheet using C# https://www.youtube.com/watch?v=O5Dnv0tfGv4

you should open like this

        Excel.Application xlApp ;
        Excel.Workbook xlWorkBook ;
        Excel.Worksheet xlWorkSheet ;
        object misValue = System.Reflection.Missing.Value;

        xlApp = new Excel.ApplicationClass();
        xlWorkBook = xlApp.Workbooks.Open("csharp.net-informations.xls", 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
        xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);

source : http://csharp.net-informations.com/excel/csharp-open-excel.htm

ruden

For opening a file, try this:

objexcel.Workbooks.Open(@"C:\YourPath\YourExcelFile.xls",
    missing, missing, missing, missing, missing, missing, missing,
    missing, missing, missing, missing, missing,missing, missing);

You must supply those stupid looking 'missing' arguments. If you were writing the same code in VB.Net you wouldn't have needed them, but you can't avoid them in C#.

It's easier to help you if you say what's wrong as well, or what fails when you run it.

But from a quick glance you've confused a few things.

The following doesn't work because of a couple of issues.

if (Directory("C:\\csharp\\error report1.xls") = "")

What you are trying to do is creating a new Directory object that should point to a file and then check if there was any errors.

What you are actually doing is trying to call a function named Directory() and then assign a string to the result. This won't work since 1/ you don't have a function named Directory(string str) and you cannot assign to the result from a function (you can only assign a value to a variable).

What you should do (for this line at least) is the following

FileInfo fi = new FileInfo("C:\\csharp\\error report1.xls");
if(!fi.Exists)
{
    // Create the xl file here
}
else
{
    // Open file here
}

As to why the Excel code doesn't work, you have to check the documentation for the Excel library which google should be able to provide for you.

Microsoft.Office.Interop.Excel.Application excapp;

excapp = new Microsoft.Office.Interop.Excel.Application();

object misval=System.Reflection.Missing.Value;

Workbook wrkbuk = new Workbook();

Worksheet wrksht = new Worksheet();

wrkbuk = excapp.Workbooks._Open(@"C:\Users\...\..._template_v1.0.xlsx", misval, misval, 
misval, misval, misval, misval, misval, misval, misval, misval, misval, misval);

wrksht = (Microsoft.Office.Interop.Excel.Worksheet)wrkbuk.Worksheets.get_Item(2);

Is this a commercial application or some hobbyist / open source software?

I'm asking this because in my experience, all free .NET Excel handling alternatives have serious problems, for different reasons. For hobbyist things, I usually end up porting jExcelApi from Java to C# and using it.

But if this is a commercial application, you would be better off by purchasing a third party library, like Aspose.Cells. Believe me, it totally worths it as it saves a lot of time and time ain't free.

For editing Excel files from within a C# application, I recently started using NPOI. I'm very satisfied with it.

Code :

 private void button1_Click(object sender, EventArgs e)
     {
       
        textBox1.Enabled=false;
       
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Filter = "Excell File |*.xlsx;*,xlsx";
            if (ofd.ShowDialog() == DialogResult.OK)
            {
                string extn = Path.GetExtension(ofd.FileName);
                if (extn.Equals(".xls") || extn.Equals(".xlsx"))
                {
                    filename = ofd.FileName;
                    
                    if (filename != "")
                    {
                        try
                        {
                            string excelfilename = Path.GetFileName(filename);
                            

                        }
                        catch (Exception ew)
                        {
                            MessageBox.Show("Errror:" + ew.ToString());
                        }
                    }
                }
            }