I would like to replace from a number of 16 digits, it's 5th to 10th digit.
How can that be achieved with a regular expression (C#)?
The way to do it is to capture in the inner and outer portions separately, like this:
// Split into 2 groups of 5 digits and 1 of 6
string regex = "(\\d{5})(\\d{5})(\\d{6})";
// Insert ABCDEF in the middle of
// match 1 and match 3
string replaceRegex = "${1}ABCDE${3}";
string testString = "1234567890999999";
string result = Regex.Replace(testString, regex, replaceRegex);
// result = '12345ABCDE999999'
Why use a regular expression? If by "number of 16 digits", you mean a 16 character long string representation of a number, then you'd probably be better off just using substring.
string input = "0000567890000000";
var output = input.Substring(0, 4) + "222222" + input.Substring(10, 6);
Or did you mean you want to swap the 5th and 10th digits? Your question isn't very clear.
Use the regular expression (?<=^\d{4})\d{6}(?=\d{6}$) to achieve it without capture groups.
It looks for 6 consecutive digits (5th to 10th inclusively) that are preceded by the first 4 digits and the last 6 digits of the string.
Regex.Replace("1234567890123456", #"(?<=^\d{4})\d{6}(?=\d{6}$)", "replacement");
Got it...
by creating 3 capturing groups:
([\d]{5})([\d]{5})([\d]{6})
keep capturing group1 and 3 and replace group2 with stars (or whatever)
$1*****$3
C# code below
string resultString = null;
try {
resultString = Regex.Replace(subjectString, #"([\d]{5})([\d]{5})([\d]{6})", "$1*****$2", RegexOptions.Singleline);
} catch (ArgumentException ex) {
// Syntax error in the regular expression
}
Related
I need to check if a string begins with 2 specific letters and then is followed by any 4 numbers.
the 2 letters are "BR" so BR1234 would be valid so would BR7412 for example.
what bit of code do I need to check that the string is a match with the Regex in C#?
the regex I have written is below, there is probably a more efficient way of writing this (I'm new to RegEx)
[B][R][0-9][0-9][0-9][0-9]
You can use this:
Regex regex = new Regex(#"^BR\d{4}");
^ defines the start of the string (so there should be no other characters before BR)
BR matches - well - BR
\d is a digit (0-9)
{4} says there must be exactly 4 of the previously mentioned group (\d)
You did not specify what is allowed to follow the four digits. If this should be the end of the string, add a $.
Usage in C#:
string matching = "BR1234";
string notMatching = "someOther";
Regex regex = new Regex(#"^BR\d{4}");
bool doesMatch = regex.IsMatch(matching); // true
doesMatch = regex.IsMatch(notMatching); // false;
BR\d{4}
Some text to make answer at least 30 characters long :)
I want to check if an input string follows a pattern and if it does extract information from it.
My pattern is like this Episode 000 (Season 00). The 00s are numbers that can range from 0-9. Now I want to check if this input Episode 094 (Season 02) matches this pattern and because it does it should then extract those two numbers, so I end up with two integer variables 94 & 2:
string latestFile = "Episode 094 (Season 02)";
if (!Regex.IsMatch(latestFile, #"^(Episode)\s[0-9][0-9][0-9]\s\((Season)\s[0-9][0-9]\)$"))
return
int Episode = Int32.Parse(Regex.Match(latestFile, #"\d+").Value);
int Season = Int32.Parse(Regex.Match(latestFile, #"\d+").Value);
The first part where I check if the overall string matches the pattern works, but I think it can be improved. For the second part, where I actually extract the numbers I'm stuck and what I posted above obviously doesn't works, because it grabs all digits from the string. So if anyone of you could help me figure out how to only extract the three number characters after Episode and the two characters after Season that would be great.
^Episode (\d{1,3}) \(Season (\d{1,2})\)$
Captures the 2 numbers (even with length 1 to 3/2) and gives them back as a group.
You can go even further and name your groups:
^Episode (?<episode>\d{1,3}) \(Season (?<season>\d{1,2})\)$
and then call them.
Example for using groups:
string pattern = #"abc(?<firstGroup>\d{1,3})abc";
string input = "abc234abc";
Regex rgx = new Regex(pattern);
Match match = rgx.Match(input);
string result = match.Groups["firstGroup"].Value; //=> 234
You can see what the expressions mean and test them here
In your regex ^(Episode)\s[0-9][0-9][0-9]\s\((Season)\s[0-9][0-9]\)$ you are capturing Episode and Season in a capturing group, but what you actually want to capture is the digits. You could switch your capturing groups like this:
^Episode\s([0-9][0-9][0-9])\s\(Season\s([0-9][0-9])\)$
Matching 3 digits in this way [0-9][0-9][0-9] can be written as \d{3} and [0-9][0-9] as \d{2}.
That would look like ^Episode\s(\d{3})\s\(Season\s(\d{2})\)$
To match one or more digits you could use \d+.
The \s is a matches a whitespace character. You could use \s or a whitespace.
Your regex could look like:
^Episode (\d{3}) \(Season (\d{2})\)$
string latestFile = "Episode 094 (Season 02)";
GroupCollection groups = Regex.Match(latestFile, #"^Episode (\d{3}) \(Season (\d{2})\)$").Groups;
int Episode = Int32.Parse(groups[1].Value);
int Season = Int32.Parse(groups[2].Value);
Console.WriteLine(Episode);
Console.WriteLine(Season);
That would result in:
94
2
Demo C#
I am trying to write a regex expression to use it in C#
The use of the regex is to get a substring of the input according to the input size
The regex expression target
If the input size less than 13 then get the full input
Else if the input size is greater than 25 then get from the input the substring from index 3 till index 16 (so that I skip the first three chars)
Here is what I came with till now
(?(?=.{25,}).{3}(.{13})|(?(?=.{0,13})(.{0,13})))
This is not working since when the input size is greater than 25 the result is not trimming the first three chars
Check it here
Note that a non-regex solution is rather trivial:
public string check(string s)
{
var res = "";
if (s.Length>=25)
res = s.Substring(3,13);
else if (s.Length <= 13)
res = s;
return res;
}
If you want to use a regex, you may use
^(?=.{25,}).{3}(?<res>.{13})|^(?=.{0,13}$)(?<res>.*)
See the regex demo. Compile with RegexOptions.Singleline to support newlines in the input.
Details
^ - start of string
(?=.{25,}) - if there are 25 or more chars after the start of string, match
.{3} - any 3 chars
(?<res>.{13}) - and capture 13 chars into res group
| - or
^(?=.{0,13}$) - make sure there are no more than 0 to 13 chars in the string and then
(?<res>.*) - grab the whole string (if no RegexOptions.Singleline is used, only 1 line will be matched).
Use it as
var res = "";
var m = Regex.Match(s, #"^(?=.{25,}).{3}(?<res>.{13})|^(?=.{0,13}$)(?<res>.*)")
if (m.Success)
{
res = m.Groups["res"].Value;
}
See a C# demo.
I'm searching for a regular expression that will extract 0263563
from
;010263563=2119?
and 0267829
from
%00000026782904?;010267829=4119?
(Must be the same regular expression).
Start at the 3rd character after the semicolon and take 7 characters.
;..(\d{7})
or more general:
;..(.{7})
Or according to comment : "To clarify characters to take are digits"
;\d\d(\d{7})
Well, you need this:
;\d{2}(\d+)
The First group will contain the number you want.
;[\S]{2}([\S]{7})
Since you said characters and not numbers, but it would work either way
For rules that are that precise (start 3 chars after ;, then next 7), you could use a plain substring:
string s = "%00000026782904?;010267829=4119?";
var pos = s.IndexOf(';');
var number = s.Substring(pos+3, 7);
And of course, test whether that IndexOf really found the ;
The below regex would exactly 7 digits which must be preceded by a ; , any two characters.
(?<=;.{2})\d{7}
Code:
String input = #";010263563=2119?
%00000026782904?;010267829=4119?";
Regex rgx = new Regex(#"(?<=;.{2})\d{7}");
foreach (Match m in rgx.Matches(input))
Console.WriteLine(m.Groups[0].Value);
IDEONE
Output:
0263563
0267829
Assuming regex is not an absolute requirement, you could use:
var input = "%00000026782904?;010267829=4119?";
// output will be: 0267829
var digits = input.SkipWhile(x => x != ';').Skip(3).Take(7).ToArray();
var output = new string(digits);
I would like to use regex instead of string.replace() to get the first 6 chars of a string and the last 4 chars of the same string and substitute it with another character: & for example. The string is always with 16 chars. Im doing some research but i never worked with regex before. Thanks
If you prefer to use regular expression, you could use the following. The dot . will match any character except a newline sequence, so you can specify {n} to match exactly n times and use beginning/end of string anchors.
String r = Regex.Replace("123456foobar7890", #"^.{6}|.{4}$",
m => new string('&', m.ToString().Length));
Console.WriteLine(r); //=> "&&&&&&foobar&&&&"
If you want to invert the logic, replacing the middle portion of your string you can use Positive Lookbehind.
String r = Regex.Replace("123456foobar7890", #"(?<=^.{6}).{6}",
m => new string('&', m.ToString().Length));
Console.WriteLine(r); //=> "123456&&&&&&7890"