C＃正则表达式以匹配时间

Question

I am trying to write a Regex to match the "time" ( hh:mm:ss ) for example 11:20:00 , 18:02:22 or 6:00:00 .

I wrote the following but it does not work as expected. It matches when its the only thing in the string or if its the first value in the string. For example:

string timepattern = @"^([0-1]?\d|2[0-3])(?::([0-5]?\d))?(?::([0-5]?\d))?";
string value = "30.Jul.2019 This the line I want to match 15:04:09"
var returnedValue = Regex.Match(line, timepattern);

returnedValue would yield 3 . But I want the whole time.

Answer 1

If you only want the time and don't care about the rest of the line, it's ([0-1]?\\d|2[0-3]):(?:([0-5]?\\d))?:(?:([0-5]?\\d))?

Try it here!

Answer 2

    string timepattern = @"(?:2[0-3]|[01]?[0-9])[:.][0-5]?[0-9][:.][0-5]?[0-9]";
    string value = "30.Jul.2019 This the line I want to match 15:04:09";
    var returnedValue = Regex.Match(value, timepattern);

I use the following web site to lookup regexs, it may be useful for you...

http://regexlib.com/Search.aspx?k=time+hh%3amm%3ass&c=-1&m=-1&ps=20

Another nice information source, https://www.regular-expressions.info/tutorial.html