如何使用正则表达式从字符串中提取日期

Question

im looking for regex which can extract the date from the following html

<p>British Medical Journal, 29.9.12, pp.37-41.</p>

and convert it in the format 29/09/12

Answer 1

Match this pattern: -

(\d+)[.](\d+)[.](\d+)

and replace with: -

$1/$2/$3

\\d is used to match digits . Using it with quantifier (+) , you would match one or more digits. Now, in regex, a dot(.) is a metacharacter, that matches any character. To match a period literally, you would need to either escape it, or use it inside a character class.

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To convert to a specific Date Format , eg: - convert 9 -> 09 , you can make use of a MatchEvaluator : -

string input = "British Medical Journal, 29.9.12, pp.37-41.";
Regex reg = new Regex(@"(\d+)[.](\d+)[.](\d+)");
string result = reg.Replace(input, delegate(Match m) {
    return m => DateTime.Now.ToString("dd/MM/yy")
});

You can check whether it works or not.

Answer 2

Here is the regex pattern: \\d{1,2}\\.\\d{1,2}\\.\\d{1,2} .

And here is the example of how to parse this string to DateTime:

DateTime.ParseExact("29.9.12", "d.M.yy", CultureInfo.InvariantCulture);

Answer 3

(\\d{4})[-](\\d{2})[-](\\d{2})使用此正则表达式选择2017年1月23日的格式日期