Reading dates from OpenXml Excel files

Question

I\'m trying to read data from the .xlsx files using SharpZipLib to unpack it (in memory) and reading the inner xml files. Everything is fine but recognizing the dates - they

Answer 1

Cells may have styles. These are uints that index cellXfs in the styleSheet. Each cellXfs item contains a set of attributes. The most important is NumberFormatID. If its value falls in the range 14-22 it is a "standard" date. If it falls in the range 165 - 180, it is a "formatted" date and will have a corresponding NumberingFormat attribute.

Standard Date

[x:c r="A2" s="2"][x:v]38046[/x:v][/x:c]

[x:xf numFmtId="14" fontId="0" fillId="0" borderId="0" xfId="0" applyNumberFormat="1" /] (ordinal position 2)

Formatted Date

[x:c r="A4" s="4"][x:v]38048[/x:v][/x:c]

[x:xf numFmtId="166" fontId="0" fillId="0" borderId="0" xfId="0" applyNumberFormat="1" /](ordinal position 4)

[x:numFmt numFmtId="166" formatCode="m/d;@" /]

This code extracts a list of style IDs that correspond to these date formats.

  private void GetDateStyles()
  {
     //
     // The only way to tell dates from numbers is by looking at the style index. 
     // This indexes cellXfs, which contains NumberFormatIds, which index NumberingFormats.
     // This method creates a list of the style indexes that pertain to dates.
     WorkbookStylesPart workbookStylesPart = (WorkbookStylesPart) UriPartDictionary["/xl/styles.xml"];
     Stylesheet styleSheet = workbookStylesPart.Stylesheet;
     CellFormats  cellFormats = styleSheet.CellFormats;

     int i = 0;
     foreach (CellFormat cellFormat in cellFormats)
     {
        uint numberFormatId = cellFormat.NumberFormatId;
        if ((numberFormatId >= 14 && numberFormatId <= 22) 
        || (numberFormatId >= 165u && numberFormatId <= 180u))
        {
           _DateStyles.Add(i.ToString());
        }
        i++;
     }