C# Code to Get Previous Date

[Joe Caverly]

Requires CSScript Plugin (attached)
Ref: CsScript .NET plugin for TCC v36

Requires @PREVDATE UDF
Ref: Get yesterdays date with UDF @PREVDATE

using System;
using System.Globalization;

public class Program
{
    public static void Main(string[] args)
    {
        if (args == null || args.Length < 1)
        {
            Console.Error.WriteLine("Usage: <program> <date-YYYY-MM-DD>");
            return;
        }

        try
        {
            // Expecting format like: 2026-07-23
            var inputDate = DateTime.ParseExact(
                args[0],
                "yyyy-MM-dd",
                CultureInfo.InvariantCulture,
                DateTimeStyles.None);

            var yesterday = inputDate.Date.AddDays(-1);
            Console.WriteLine(yesterday.ToString("yyyy-MM-dd"));
        }
        catch (Exception ex)
        {
            Console.Error.WriteLine(ex.ToString());
        }
    }
}

Proof;

plugin /l csscript.dll

plugin /i csscript
Module:      csscript.dll
Name:        CsScript
Author:      Joe Caverly
Email:       [email protected]
Web:         https://github.com/joec4281?tab=repositories
Description: CsScript command to run CSharp code
Implements:  CSSCRIPT
Version:     2026.7  Build 21

csscript prevdate.csx
Usage: <program> <date-YYYY-MM-DD>

csscript prevdate.csx 2026-07-23
2026-07-22

R:\>csscript .\prevdate.csx %@prevdate[%_isodate]
2026-07-21

Joe