title: For Loop in C# not looping
body: <p>I have an issue with a Loop that doesn't actually loop. I've posted a simplified version of my code below. Basically, using the NPOI excel library, I have an excel file with data on the first and second sheet, so I need to do a loop to get through both sheets. </p>
  
  <p>Below is what I have done so far, however this only works through the first sheet and then exits. It fails to increment the variable w. As you can see, there are other loops implemented in this code which function fine so I don't get it.</p>
  
  <p>It's been a very long day and perhaps I'm missing something very simple. I could have it placed wrong or something. If anyone else can spot what I might be doing wrong I'd be very grateful :)</p>
  
  <pre><code>public class SalesFileProcessor : ISalesProcessor
      {
          public List&lt;FTPSalesRow&gt; ProcessSalesFile(string filename)
          {
              try
              {
  
              using (FileStream fs = File.Open(filename, FileMode.Open, FileAccess.Read))
              {
                  int numberOfSheets = 2;
  //Loop through sheets - does not work
                  for (int w = 0; w &lt;= numberOfSheets; w++)
                  {
                      HSSFWorkbook templateWorkbook = new HSSFWorkbook(fs);
  
                      HSSFSheet sheet = templateWorkbook.GetSheetAt(w);
                      HSSFRow row = null;
  
  
                      for (int i = 1; i &lt;= sheet.LastRowNum; i++)
                      {
                          FTPSalesDetails t = null;
                          int currentColumn = 0;
  
                          try
                          {
                              ModelContainer ctn = new ModelContainer();
  
                              row = sheet.GetRow(i);
  
                              if (row == null)
                              {
                                  continue;
                              }
  
                              t = new FTPSalesDetails
                              {
                                  RowNumber = i,
                                  InvoiceDate = GetCellValue(row.GetCell(0)),
                                  CountrySoldIn = GetCellValue(row.GetCell(1)),
                                  NetUnitsSold = GetCellValue(row.GetCell(2)),
                                  Item = GetCellValue(row.GetCell(3)),
                                  ProductCode = GetCellValue(row.GetCell(5)),
                              };
  
                              if (t.ProductCode == null &amp;&amp; t.NetUnitsSold == null)
                              {
                                  return null;
                              }
  
                              int Qty = int.Parse(t.NetUnitsSold);
  
  
                              for (int x = 0; x &lt; Qty; x++)
                              {
                                  ItemSale ts = new ItemSale
                                  {
                                      ItemID = GetItemID(t.ProductCode),
                                      ManufacturerID = GetManufacturerID("Samsung"),
                                      DateSold = DateTime.Now,
                                  };
  
                                  ctn.AddToItemSales(ts);
                                  ctn.SaveChanges();
                              }
                          }
                          catch (IndexOutOfRangeException) { }
                      }
                  } //End Loop - the one that doesn't work
              }
          }
          catch (IOException exp)
          {
              throw new FTPSalesFileProcessingException("Could not open the Sales data file", exp);
          }
          catch (Exception exp)
          {
              throw new FTPSalesFileProcessingException("An unknown eror occured during processing the file", exp);
          }
  
          return null;
      }
  </code></pre>