还记得小学时候学的九九乘法表吗？这节我们一起学习利用NPOI通过C#代码生成一张Excel的九九乘法表。要生成九九乘法表，循环肯定是少不了的，如下：
HSSFSheet sheet1 = hssfworkbook.CreateSheet("Sheet1");
HSSFRow row;
HSSFCell cell;
for (int rowIndex = 0; rowIndex < 9; rowIndex++)
{
     row = sheet1.CreateRow(rowIndex);
     for (int colIndex = 0; colIndex <= rowIndex; colIndex++)
     {
           cell = row.CreateCell(colIndex);
           cell.SetCellValue(String.Format("{0}*{1}={2}", rowIndex + 1, colIndex + 1, (rowIndex + 1) * (colIndex + 1)));
     }
}

      代码其实很简单，就是循环调用cell.SetCellValue(str)写入9行数据，每一行写的单元格数量随行数递增。执行完后生成的Excel样式如下：


完整的代码如下：
Code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NPOI.HSSF.UserModel;
using System.IO;
using NPOI.HPSF;

namespace TimesTables
{
    public class Program
    {
        static HSSFWorkbook hssfworkbook;

        static void Main(string[] args)
        {
            InitializeWorkbook();

            HSSFSheet sheet1 = hssfworkbook.CreateSheet("Sheet1");
            HSSFRow row;
            HSSFCell cell;
            for (int rowIndex = 0; rowIndex < 9; rowIndex++)
            {
                row = sheet1.CreateRow(rowIndex);
                for (int colIndex = 0; colIndex <= rowIndex; colIndex++)
                {
                    cell = row.CreateCell(colIndex);
                    cell.SetCellValue(String.Format("{0}*{1}={2}", rowIndex + 1, colIndex + 1, (rowIndex + 1) * (colIndex + 1)));
                }
            }

            WriteToFile();
        }

        static void WriteToFile()
        {
            //Write the stream data of workbook to the root directory
            FileStream file = new FileStream(@"test.xls", FileMode.Create);
            hssfworkbook.Write(file);
            file.Close();
        }

        static void InitializeWorkbook()
        {
            hssfworkbook = new HSSFWorkbook();

            //create a entry of DocumentSummaryInformation
            DocumentSummaryInformation dsi = PropertySetFactory.CreateDocumentSummaryInformation();
            dsi.Company = "NPOI Team";
            hssfworkbook.DocumentSummaryInformation = dsi;

            //create a entry of SummaryInformation
            SummaryInformation si = PropertySetFactory.CreateSummaryInformation();
            si.Subject = "NPOI SDK Example";
            hssfworkbook.SummaryInformation = si;
        }
    }
}