Tag: #datetime
3 articles
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![Excel Number Format Codes, Decoded — #,##0, [Red], ;;; and K/M Suffixes in a C# App](/images/articles/excel-number-format-codes.svg)
Excel Number Format Codes, Decoded — #,##0, [Red], ;;; and K/M Suffixes in a C# App
#,##0;[Red]-#,##0;"-" looks like line noise, but it is a small language — four sections, digit placeholders, colors, conditions and literal text — and once you can read it you can write the code you actually need. This guide decodes Excel's custom number formats: thousands and millions scaling, hiding values, units, [h]:mm for timesheets, and why three cells showing 33 can total 100. Then it applies the same codes in C# with ReoGrid V5, where a code copied out of Excel works as-is and survives the trip to XLSX.
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EDATE, EOMONTH, WORKDAY, NETWORKDAYS — Business Date Calculations with Spreadsheet Formulas in C#
"Due at the end of next month," "ship within 5 business days," "remind 3 business days before the deadline" — business apps are full of date rules that are surprisingly fiddly to hand-code with DateTime. Excel solved them long ago with EDATE, EOMONTH, WORKDAY, and NETWORKDAYS. This guide sorts out what each one does, the classic off-by-one traps, and how ReoGrid (supported in V4.5) runs the same formulas inside a WinForms / WPF app, without Office.
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Japanese Era (Wareki) Date Cells in C# — Display 令和8年6月6日 While the Data Stays a DateTime
Invoices, contracts, birthdates — apps for the Japanese market must show dates in the era calendar (Reiwa, Heisei, Showa). Convert to strings and you break sorting and formulas. With ReoGrid, one format pattern shows wareki while every cell keeps a real DateTime.