程序代码：

using System;
using Microsoft.Office.Interop.Excel;

namespace TestOffice
{
    class Program
    {
        static void Main(string[] args)
        {
            Application excel = new Application();
            Workbook workbook = excel.Workbooks.Open(@"C:\tmp\test\test.xls");

            for (int i = 1; i <= workbook.Sheets.Count; ++i)
            {
                Worksheet sheet = workbook.Sheets[i];

                Range firstCell = sheet.UsedRange[1, 1];

                object[,] data = sheet.UsedRange.get_Value();

                if (data != null)
                {
                    for (int row = 1; row <= data.GetLength(0); ++row)
                    {
                        for (int column = 1; column <= data.GetLength(1); ++column)
                        {
                            if (data[row, column] != null)
                            {
                                Console.WriteLine("Found data in sheet {0} at row {1} and column {2} : {3}", sheet.Name, row + firstCell.Row - 1, column + firstCell.Column - 1, data[row, column]);
                            }
                        }
                    }
                }
            }

            Console.ReadLine();
        }
    }
}