I'm trying to come up with regular expression which will split full names.
The first part is validation - I want to make sure the name matches the pattern "Name Name" or "Name MI Name", where MI can be one character optionally followed by a period. This weeds out complex names like "Jose Jacinto De La Pena" - and that's fine. The expression I came up with is ^([a-zA-Z]+\s)([a-zA-Z](\.?)\s){0,1}([a-zA-Z'-]+)$ and it seems to do the job.
But how do I modify it to split the name into two parts only? If middle initial is present, I want it to be a part of the first "name", in other words "James T. Kirk" should be split into "James T." and "Kirk". TIA.
Just add some parenthesis
^(([a-z]+\s)([a-z](\.?))\s){0,1}([a-z'-]+)$
Your match will be in group 1 now
string resultString = null;
try {
resultString = Regex.Match(subjectString, #"^(([a-z]+\s)([a-z](\.?))\s){0,1}([a-z'-]+)$", RegexOptions.IgnoreCase).Groups[1].Value;
} catch (ArgumentException ex) {
// Syntax error in the regular expression
}
Also, I made the regex case insensitive so that you can make it shorter (no a-zA-Z but a-z)
Update 1
The number groups don't work well for the case there is no initial so I wrote the regex from sratch
^(\w+\s(\w\.\s)?)(\w+)$
\w stands for any word charater and this is maybe what you need (you can replace it by a-z if that works better)
Update 2
There is a nice feature in C# where you can name your captures
^(?<First>\w+\s(?:\w\.\s)?)(?<Last>\w+)$
Now you can refer to the group by name instead of number (think it's a bit more readable)
var subjectString = "James T. Kirk";
Regex regexObj = new Regex(#"^(?<First>\w+\s(?:\w\.\s)?)(?<Last>\w+)$", RegexOptions.IgnoreCase);
var groups = regexObj.Match(subjectString).Groups;
var firstName = groups["First"].Value;
var lastName = groups["Last"].Value;
You can accomplish this by making what is currently your second capturing group a non-capturing group by adding ?: just before the opening parentheses, and then moving that entire second group into the end of the first group, so it would become the following:
^([a-zA-Z]+\s(?:[a-zA-Z](\.?)\s)?)([a-zA-Z'-]+)
Note that I also replaced the {0,1} with ?, because they are equivalent.
This will result in two capturing groups, one for the first name and middle initial (if it exists), and one for the last name.
I'm not sure if you want this way, but there is a method of doing it without regular expressions.
If the name is in the form of Name Name then you could do this:
// fullName is a string that has the full name, in the form of 'Name Name'
string firstName = fullName.Split(' ')[0];
string lastName = fullName.Split(' ')[1];
And if the name is in the form of Name MIName then you can do this:
string firstName = fullName.Split('.')[0] + ".";
string lastName = fullName.Split('.')[1].Trim();
Hope this helps!
Just put the optional part in the first capturing group:
(?i)^([a-z]+(?:\s[a-z]\.?)?)\s([a-z'-]+)$
Related
Say I have the string "User Name:firstname.surname" contained in a larger string how can I use a regular expression to just get the firstname.surname part?
Every method i have tried returns the string "User Name:firstname.surname" then I have to do a string replace on "User Name:" to an empty string.
Could back references be of use here?
Edit:
The longer string could contain "Account Name: firstname.surname" hence why I want to match the "User Name:" part of the string aswell to just get that value.
I like to use named groups:
Match m = Regex.Match("User Name:first.sur", #"User Name:(?<name>\w+\.\w+)");
if(m.Success)
{
string name = m.Groups["name"].Value;
}
Putting the ?<something> at the beginning of a group in parentheses (e.g. (?<something>...)) allows you to get the value from the match using something as a key (e.g. from m.Groups["something"].Value)
If you didn't want to go to the trouble of naming your groups, you could say
Match m = Regex.Match("User Name:first.sur", #"User Name:(\w+\.\w+)");
if(m.Success)
{
string name = m.Groups[1].Value;
}
and just get the first thing that matches. (Note that the first parenthesized group is at index 1; the whole expression that matches is at index 0)
You could also try the concept of "lookaround". This is a kind of zero-width assertion, meaning it will match characters but it won't capture them in the result.
In your case, we could take a positive lookbehind: we want what's behind the target string "firstname.surname" to be equal to "User Name:".
Positive lookbehind operator: (?<=StringBehind)StringWeWant
This can be achieved like this, for instance (a little Java example, using string replace):
String test = "Account Name: firstname.surname; User Name:firstname.surname";
String regex = "(?<=User Name:)firstname.surname";
String replacement = "James.Bond";
System.out.println(test.replaceAll(regex, replacement));
This replaces only the "firstname.surname" strings that are preceeded by "User Name:" without replacing the "User Name:" itself - which is not returned by the regex, only matched.
OUTPUT: Account Name: firstname.surname; User Name:James.Bond
That is, if the language you're using supports this kind of operations
Make a group with parantheses, then get it from the Match.Groups collection, like this:
string s = "User Name:firstname.surname";
Regex re = new Regex(#"User Name:(.*\..*)");
Match match = re.Match(s);
if (match.Success)
{
MessageBox.Show(match.Groups[1].Value);
}
(note: the first group, with index 0, is the whole match)
All regular expression libraries I have used allow you to define groups in the regular expression using parentheses, and then access that group from the result.
So, your regexp might look like: User name:([^.].[^.])
The complete match is group 0. The part that matches inside the parentheses is group 1.
I currently have a string which looks like this when it is returned :
//This is the url string
// the-great-debate---toilet-paper-over-or-under-the-roll
string name = string.Format("{0}",url);
name = Regex.Replace(name, "-", " ");
And when I perform the following Regex operation it becomes like this :
the great debate toilet paper over or under the roll
However, like I mentioned in the question, I want to be able to apply regex to the url string so that I have the following output:-
the great debate - toilet paper over or under the roll
I would really appreciate any assistance.
[EDIT] However, not all the strings look like this, some of them just have a single hyphen so the above method work
world-water-day-2016
and it changes to
world water day 2016
but for this one:
the-great-debate---toilet-paper-over-or-under-the-roll
I need a way to check if the string has 3 hyphens than replace those 3 hyphens with [space][hyphen][space]. And than replace all the remaining single hyphens between the words with space.
First of all, there is always a very naive solution to this kind of problem: you replace your specific matches in context with some chars that are not usually used in the current environment and after replacing generic substrings you may replace the temporary substrings with the necessary exception.
var name = url.Replace("---", "[ \uFFFD ]").Replace("-", " ").Replace("[ \uFFFD ]", " - ");
You may also use a regex based replacement that matches either a 3-hyphen substring capturing it, or just match a single hyphen, and then check if Group 1 matched inside a match evaluator (the third parameter to Regex.Replace can be a Match evaluator method).
It will look like
var name = Regex.Replace(url, #"(---)|-", m => m.Groups[1].Success ? " - " : " ");
See the C# demo.
So, when (---) part matches, the 3 hyphens are put into Group 1 and the .Success property is set to true. Thus, m => m.Groups[1].Success ? " - " : " " replaces 3 hyphens with space+-+space and 1 hyphen (that may be actually 1 of the 2 consecutive hyphens) with a space.
Here's a solution using LINQ rather than Regex:
var str = "the-great-debate---toilet-paper-over-or-under-the-roll";
var result = str.Split(new string[] {"---"}, StringSplitOptions.None)
.Select(s => s.Replace("-", " "))
.Aggregate((c,n) => $"{c} - {n}");
// result = "the great debate - toilet paper over or under the roll"
Split the string up based on the ---, then remove hyphens from each substring, then join them back together.
The easy way:
name = Regex.Replace(name, "\b-|-\b", " ");
The show-off way:
name = Regex.Replace(name, "(\b)?-(?(1)|\b)", " ");
I have a C# regular expression to match author names in a text document that is written as:
"author":"AUTHOR'S NAME"
The regex is as follows:
new Regex("\"author\":\"[A-Za-z0-9]*\\s?[A-Za-z0-9]*")
This returns "author":"AUTHOR'S NAME. However, I don't want the quotation marks or the word Author before. I just want the name.
Could anyone help me get the expected value please?
Use regex groups to get a part of the string. ( ) acts as a capture group and can be accessed by the .Groups field.
.Groups[0] matches the whole string
.Groups[1] matches the first group (and so on)
string pattern = "\"author\":\"([A-Za-z0-9]*\\s?[A-Za-z0-9]*)\"";
var match = Regex.Match("\"author\":\"Name123\"", pattern);
string authorName = match.Groups[1];
You can also use look-around approach to only get a match value:
var txt = "\"author\":\"AUTHOR'S NAME\"";
var rgx = new Regex(#"(?<=""author"":"")[^""]+(?="")");
var result = rgx.Match(txt).Value;
My regex yields 555,020 iterations per second speed with this input string, which should suffice.
result will be AUTHOR'S NAME.
(?<="author":") checks if we have "author":" before the match, [^"]+ looks safe since you only want to match alphanumerics and space between the quotes, and (?=") is checking the trailing quote.
I'm having a hard time with regular expressions in C#.
I have a joined string with name and surname, and need only the first letter of name and a surname:
string input = "NameSurname";
string output = "NSurname";
So basically it's always first letter of input string, plus what comes after second occurence of capital letter.
Thank you in advance for help.
I don't know why people are down-voting these posts.
Try this
var name = Regex.Replace("NameSurname", #"^(\w)[^A-Z]*(.*)", "$1$2")
^(\w) matches the first character and retains it in $1.
[^A-Z]* matches any subsequent characters that aren't upper case letters.
(.*) matches all subsequent characters and retains them in $2.
So we replace "NameSurname" with $1="N" + $2="Surname"
Do you have to use regex? It might be easier to use Linq.
For example:
var charsFromSecondUppercaseChar = input.Skip(1).SkipWhile(c => !char.IsUpper(c));
string output = input[0] + new string(charsFromSecondUppercaseChar.ToArray());
I am trying to create a regex in C# to extract the artist, track number and song title from a filename named like: 01.artist - title.mp3
Right now I can't get the thing to work, and am having problems finding much relevant help online.
Here is what I have so far:
string fileRegex = "(?<trackNo>\\d{1,3})\\.(<artist>[a-z])\\s-\\s(<title>[a-z])\\.mp3";
Regex r = new Regex(fileRegex);
Match m = r.Match(song.Name); // song.Name is the filname
if (m.Success)
{
Console.WriteLine("Artist is {0}", m.Groups["artist"]);
}
else
{
Console.WriteLine("no match");
}
I'm not getting any matches at all, and all help is appreciated!
You might want to put ?'s before the <> tags in all your groupings, and put a + sign after your [a-z]'s, like so:
string fileRegex = "(?<trackNo>\\d{1,3})\\.(?<artist>[a-z]+)\\s-\\s(?<title>[a-z]+)\\.mp3";
Then it should work. The ?'s are required so that the contents of the angled brackets <> are interpreted as a grouping name, and the +'s are required to match 1 or more repetitions of the last element, which is any character between (and including) a-z here.
Your artist and title groups are matching exactly one character. Try:
"(?<trackNo>\\d{1,3})\\.(?<artist>[a-z]+\\s-\\s(?<title>[a-z]+)\\.mp3"
I really recommend http://www.ultrapico.com/Expresso.htm for building regular expressions. It's brilliant and free.
P.S. i like to type my regex string literals like so:
#"(?<trackNo>\d{1,3})\.(?<artist>[a-z]+\s-\s(?<title>[a-z]+)\.mp3"
Maybe try:
"(?<trackNo>\\d{1,3})\\.(<artist>[a-z]*)\\s-\\s(<title>[a-z]*)\\.mp3";
CODE
String fileName = #"01. Pink Floyd - Another Brick in the Wall.mp3";
String regex = #"^(?<TrackNumber>[0-9]{1,3})\. ?(?<Artist>(.(?!= - ))+) - (?<Title>.+)\.mp3$";
Match match = Regex.Match(fileName, regex);
if (match.Success)
{
Console.WriteLine(match.Groups["TrackNumber"]);
Console.WriteLine(match.Groups["Artist"]);
Console.WriteLine(match.Groups["Title"]);
}
OUTPUT
01
Pink Floyd
Another Brick in the Wall