using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"([ :]) # look for : and space as possible leading characters
([\""]?) # if there's a quote, disregard it
([0-9]{4}) # find the year
- # find the 1st dash
( # Group (4)
(
((0[13578] | (10|12)) # look for 31 day months
- # followed by the 2nd dash
(0[1-9]|[1-2][0-9]|3[0-1]) # and accept days up to 31
)
| # OR...
(02 # look for Feb
- # followed by the 2nd dash
(0[1-9]|[1-2][0-9])) # and accept up to 29 days
| # OR...
((0[469]|11)) # look for 30 day months
- # followed by the 2nd dash
((0[1-9]|[1-2][0-9]|30)) # and accept up to 30 days
)
) # closes (4)
([\""]?)([ \""]?)(\s)";
string substitution = @"$1""[[$3-$4]]""$18";
string input = @"This regex changes YYYY-MM-DD to ""[[YYYY-MM-DD]]"" for Obsidian
WORKS ON:
today: 2025-03-14
birthdays: 1966-06-19
Good Dates: 2022-12-31 and 2025-02-08
old-dates: 1492-01-01 old dates could be an issue, depends on how you use your vault!
no space after colon is ok:2023-07-08
standing alone and quoted is fine: ""2021-02-28""
IGNORES:
my template version number has dots for separators (skip): 2025.12.02
No leading whitespace is questionable?2023-06-08
existing links (no leading : or space):
- [[2025-01-01]]
- [2025-01-01](https:123.com)
- ""[[2023-11-30]]""
- [[""2024-06-05""]]
Not YYYY-MM-DD dates:- 2022-1-1 Euro date: 2022-31-12 or slashes: 2021/09/15
Bad date for month: 2022-02-30 2022-04-31 2022-06-31 2022-11-31 2022-03-32
Don't match serial numbers: 2015-12-3135-89
";
RegexOptions options = RegexOptions.Multiline | RegexOptions.IgnorePatternWhitespace;
Regex regex = new Regex(pattern, options);
string result = regex.Replace(input, substitution);
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx