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Asked: 2026-05-31T01:13:54+00:00

I am using C# string content = 4 marco bob 53 AUSTRIA (Jan. 13,

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I am using C#

string content = " 4 marco bob 53 AUSTRIA (Jan. 13, 2012) – McDonald Janruary 15, 2021 July 15, 2923   June 2 2343 7/25/23 08/22/3323";

This should recognice all the dates except “4 marco bob 53” which is obviously not a datetime. However, my rules(below) match it(4 marco bob 53) and I cannot figure out how to avoid matching that(or similar examples).

I am trying to match the string above for all the date times. I wrote 3 rules to match some common date patterns.

eg:

Pattern f0: 5/2/2012

Pattern f2: 3 March 1900 or 3 Mar 1990 or 3 MAR. 1990 etc…

Pattern f3: Jan. 4, 2021 or January 4 2021, etc…

 string f0 = "([0-9]{1,2})/([0-9]{1,2})/([0-9]{2,4})";
 string f1 = "([0-9]{1,2})\\s+([jJ][aA][nN].*?|[fF][eE][bB].*?|[mM][aA][rR].*?|[aA][pP][rR].*?|[mM][aA][yY].*?|[jJ][uU][nN].*?|[jJ][uU][lL].*?|[aA][uU][gG].*?|[sS][eE][pP].*?|[oO][cC][tT].*?|[nN][oO][vV[.*?|[dD][eE][cC].*?)\\s+([0-9]{2,4})";
 string f2 = "([jJ][aA][nN].*?|[fF][eE][bB].*?|[mM][aA][rR].*?|[aA][pP][rR].*?|[mM][aA][yY].*?|[jJ][uU][nN].*?|[jJ][uU][lL].*?|[aA][uU][gG].*?|[sS][eE][pP].*?|[oO][cC][tT].*?|[nN][oO][vV[.*?|[dD][eE][cC].*?)\\s+([0-9]{1,2})[\\s,]+([0-9]{2,4})";

I am new to regex, so I am sure I am doing some silly stuff(like not using case insensitive options etc), so let me know how i can improve this as well.

This is for learning regex, not learning how to use library functions….

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1 Answer

  1. Editorial Team

    Aggregated some of the answers posted to do what I wanted. This seems to be finding dates in free text reasonably well. Thanks to all posters.

    string f0 = "(?:(\\d{1,2})/(\\d{1,2})/(\\d{2,4}))";
string f1 = "(?:(\\s\\d{1,2})\\s+(jan(?:uary){0,1}\\.{0,1}|feb(?:ruary){0,1}\\.{0,1}|mar(?:ch){0,1}\\.{0,1}|apr(?:il){0,1}\\.{0,1}|may\\.{0,1}|jun(?:e){0,1}\\.{0,1}|jul(?:y){0,1}\\.{0,1}|aug(?:ust){0,1}\\.{0,1}|sep(?:tember){0,1}\\.{0,1}|oct(?:ober){0,1}\\.{0,1}|nov(?:ember){0,1}\\.{0,1}|dec(?:ember){0,1}\\.{0,1})\\s+(\\d{2,4}))";
 string f2 = "(?:(jan(?:uary){0,1}\\.{0,1}|feb(?:ruary){0,1}\\.{0,1}|mar(?:ch){0,1}\\.{0,1}|apr(?:il){0,1}\\.{0,1}|may\\.{0,1}|jun(?:e){0,1}\\.{0,1}|jul(?:y){0,1}\\.{0,1}|aug(?:ust){0,1}\\.{0,1}|sep(?:tember){0,1}\\.{0,1}|oct(?:ober){0,1}\\.{0,1}|nov(?:ember){0,1}\\.{0,1}|dec(?:ember){0,1}\\.{0,1})\\s+([0-9]{1,2})[\\s,]+(\\d{2,4}))";

MatchCollection mc = Regex.Matches(content, f0 + "|" + f1 + "|" + f2, RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace);
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