Create Excel File with Formulas in C#

Step 1: Create new windows form application.

Step 2: In solution explorer right click on References and select Add References. Then Add Reference form will open as follows. In that select .Net tab and add "Microsoft.Office.Interop.Excel"  reference.

Step 3: Create windows from like below.

 

Step 4: Write the following code.

using System;
using System.Windows.Forms;
using Excel = Microsoft.Office.Interop.Excel;
namespace ExecelWithFormula
{
    public partial class Form1: Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void button1_Click(object sender, EventArgs e)
        {
            Excel.Application excelApp = new Excel.Application();
            Excel.Workbook workbook = null;
            Excel.Workbooks workbooks = null;
            Excel._Worksheet worksheet = null;
            workbooks = excelApp.Workbooks;
            workbook = workbooks.Add(1);
            worksheet = (Excel.Worksheet) workbook.Sheets[1];
            excelApp.Visible = true;
            worksheet.Cells[1, 1] = "Value1";
            worksheet.Cells[1, 2] = "Value2";
            worksheet.Cells[1, 3] = "Addition";
            worksheet.Cells[2, 1] = textBox1.Text;
            worksheet.Cells[2, 2] = textBox2.Text;
            worksheet.Cells[2, 3].Formula = "=SUM(A2,B2)";
        }
    }
}

Step 5: Run the application.

Step 6: Enter values of value1 and value2 and click on Create Excel

 

Step 7: Excel will be generated with SUM formula in it.

 

Step 8 : Then change value1 and value2 and check result.