C#中识别两类日期范围格式的正则表达式技术问询

Got it, let's figure out the right regex for your C# date range parsing needs. You've got three specific formats to cover, so I've put together a regex that handles all of them, plus a breakdown of how it works and how to implement it in your code.

First off, here's the complete regex that covers all three formats you mentioned:

^(?:(?:0[1-9]|1[0-2])\/(?:0[1-9]|[12]\d|3[01])\/\d{4}\s*-\s*(?:0[1-9]|1[0-2])\/(?:0[1-9]|[12]\d|3[01])\/\d{4})|(?:(January|February|March|April|May|June|July|August|September|October|November|December)\s+\d{1,2}\s*-\s*\d{1,2}\s*,\s*\d{4})$

Breakdown of the Regex #

Let's split this into two main branches that target your different date range styles:

Branch 1: Matches mm/DD/YYYY - mm/DD/YYYY #

• (?:0[1-9]|1[0-2]): Catches valid 2-digit months (01-12)
• \/: Escaped forward slash for the date separator
• (?:0[1-9]|[12]\d|3[01]): Matches valid 2-digit days (01-31)
• \/\d{4}: Grabs the 4-digit year
• \s*-\s*: Handles the hyphen between dates, with optional whitespace around it (works for both - and -)

Branch 2: Matches January 1-31,2018 and January 1 - 31, 2018 #

• (January|February|March|April|May|June|July|August|September|October|November|December): Matches full month names
• \s+\d{1,2}: Captures the start day (1 or 2 digits) with one or more spaces after the month
• \s*-\s*: Handles the hyphen between days, with optional whitespace (supports both - and -)
• \d{1,2}: Grabs the end day (1 or 2 digits)
• \s*,\s*\d{4}: Matches the comma and 4-digit year, with optional whitespace around the comma (works for both ,2018 and , 2018)

How to Use This in C# #

Here's a quick example of testing if a string matches this regex in your C# code:

using System;
using System.Text.RegularExpressions;

class DateRangeMatcher
{
    static void Main()
    {
        // Use a verbatim string to avoid escaping slashes
        string dateRangePattern = @"^(?:(?:0[1-9]|1[0-2])\/(?:0[1-9]|[12]\d|3[01])\/\d{4}\s*-\s*(?:0[1-9]|1[0-2])\/(?:0[1-9]|[12]\d|3[01])\/\d{4})|(?:(January|February|March|April|May|June|July|August|September|October|November|December)\s+\d{1,2}\s*-\s*\d{1,2}\s*,\s*\d{4})$";
        
        // Test all your target formats (plus a few edge cases)
        string[] testRanges = {
            "01/01/2018 - 01/31/2018",
            "January 1-31,2018",
            "February 1 - 28, 2018",
            "12/31/2023 - 01/01/2024",
            "March 5-10,2022",
            "April 15 - 20, 2021"
        };
        
        foreach (var range in testRanges)
        {
            bool isMatch = Regex.IsMatch(range, dateRangePattern);
            Console.WriteLine($"\"{range}\" is a valid format: {isMatch}");
        }
    }
}

Quick Notes #

• This regex is case-sensitive for month names (so january won't match). If you need case-insensitive matching, add the RegexOptions.IgnoreCase flag when calling Regex.IsMatch.
• Regex doesn't validate impossible dates like 02/30/2018 (February 30). If you need to confirm the dates are actually valid, parse the matched parts into DateTime objects in C# after matching.

内容的提问来源于stack exchange，提问作者Pradeep Venishetti