Dates, Times, and Formatting

Formatting Dates

Use an explicit culture and format string for stable text.

formatting Date format strings make output predictable for readers and programs.

Formatting Dates

format
FormattingDates.cs
Replay: real traced execution (multi-file project)
using System;
using System.Globalization;

class Program
{
    static void Main()
    {
        string format = "yyyy-MM-dd";
        DateTime date = new DateTime(2026, 7, 4);
        CultureInfo culture = CultureInfo.GetCultureInfo("en-US");
        string formatted = date.ToString(format, culture);

        Console.WriteLine($"format={format}");
        Console.WriteLine($"formatted={formatted}");
    }
}

using System;
using System.Globalization;

class Program
{
    static void Main()
    {
        string format = "MMM d, yyyy";
        DateTime date = new DateTime(2026, 7, 4);
        CultureInfo culture = CultureInfo.GetCultureInfo("en-US");
        string formatted = date.ToString(format, culture);

        Console.WriteLine($"format={format}");
        Console.WriteLine($"formatted={formatted}");
    }
}

using System;
using System.Globalization;

class Program
{
    static void Main()
    {
        string format = "dddd";
        DateTime date = new DateTime(2026, 7, 4);
        CultureInfo culture = CultureInfo.GetCultureInfo("en-US");
        string formatted = date.ToString(format, culture);

        Console.WriteLine($"format={format}");
        Console.WriteLine($"formatted={formatted}");
    }
}

  1. format ← yyyy-MM-dd, date ← 07/04/2026 00:00:00, culture ← en-US

    5{6    static void Main()7    {8        string format→ yyyy-MM-dd = "yyyy-MM-dd"; //@format="MMM d, yyyy", "dddd"9        DateTime date→ 07/04/2026 00:00:00 = new DateTime(2026, 7, 4);10        CultureInfo culture→ en-US = CultureInfo.GetCultureInfo("en-US");11        string formatted→ 2026-07-04 = date07/04/2026 00:00:00.ToString(formatyyyy-MM-dd, cultureen-US);1213        Console.WriteLine($"format={formatyyyy-MM-dd}");14        Console.WriteLine($"formatted={formatted2026-07-04}");15    }
    outputformat=yyyy-MM-dd
formatted=2026-07-04

  1. format ← MMM d, yyyy, date ← 07/04/2026 00:00:00, culture ← en-US

    5{6    static void Main()7    {8        string format→ MMM d, yyyy = "MMM d, yyyy";9        DateTime date→ 07/04/2026 00:00:00 = new DateTime(2026, 7, 4);10        CultureInfo culture→ en-US = CultureInfo.GetCultureInfo("en-US");11        string formatted→ Jul 4, 2026 = date07/04/2026 00:00:00.ToString(formatMMM d, yyyy, cultureen-US);1213        Console.WriteLine($"format={formatMMM d, yyyy}");14        Console.WriteLine($"formatted={formattedJul 4, 2026}");15    }
    outputformat=MMM d, yyyy
formatted=Jul 4, 2026

  1. format ← dddd, date ← 07/04/2026 00:00:00, culture ← en-US, formatted ← Saturday

    5{6    static void Main()7    {8        string format→ dddd = "dddd";9        DateTime date→ 07/04/2026 00:00:00 = new DateTime(2026, 7, 4);10        CultureInfo culture→ en-US = CultureInfo.GetCultureInfo("en-US");11        string formatted→ Saturday = date07/04/2026 00:00:00.ToString(formatdddd, cultureen-US);1213        Console.WriteLine($"format={formatdddd}");14        Console.WriteLine($"formatted={formattedSaturday}");15    }
    outputformat=dddd
formatted=Saturday