How to match "Parameter Name: Value" in C# Regex?

I would like to match these lines:

ParameterINeed: 758
ParameterCount: 8695
ParameterText: 56

And I would receive a parameter name and parameter value. Could you please tell me how to write Regex.Matches patter for this and how to process this data into Dictionary?

I use this code:

string Text = "ParameterINeed: 758\r\nParameterCount: 8695\r\nParameterText: 56";
string Pattern = "^(\\w+):\\s+(\\d+)$";
MatchCollection ma = Regex.Matches(Text, Pattern, RegexOptions.Singleline);

And get ma.Count = 0

From stackoverflow

• Depends on some other constaints but you could just use this.

  var regex = new Regex(@"^($<parameter>\w+):\s($<value>\d+)$");
  var dictionary = new Dictionary<string, string>();
  
  foreach(var match in regex.Matches(inputData, RegexOptions.Multiline))
  {
    dictionary.Add(
      match.Groups["parameter"].Value, 
      match.Groups["value"].Value);
  }
  

  tomaszs : It's not working. Dictionary size is 0

  bendewey : I can't test it at the moment, try playing with the RegexOptions

  bendewey : Please provide a comment when down-voting.

• Try this regex

  "^Parameter(\w+):\s+(\d+)$"
  

  You can then acces the name via Matches[1] and the value as Matches[2]. My answer is based on the idea that for the string ParameterINeed: 42 you want

  • Name: INeed
  • Value: 42

  If instead you wanted ParameterINeed for the value, you could just remove the Parameter word from the regex.

  "^(\w+):\s+(\d+)$"
  

  EDIT Responding to added code sample

  Try the following sample instead

  string Text = "ParameterINeed: 758\r\nParameterCount: 8695\r\nParameterText: 56";
  string[] lines = Text.Split("\n");
  string Pattern = @"^(\w+):\s+(\\d+)$";
  foreach ( string line in lines ) {
    MatchCollection ma = Regex.Matches(line, Pattern, RegexOptions.Singleline);
  }
  

  tomaszs : When I do it this way it matches only last parameter in text.

  tomaszs : Oh, and is there a way to do this without foreach loop?

  JaredPar : @tomaszs, generally speaking it's harder to get a regex to play around with a new line. You can use one but it makes it harder to reason about the values within the match collection. Is there a reason you don't want to process it in a loop?

  tomaszs : @JaredPar - I would like to get rid of any kind of splits and loops so that it will be pure, independent Regex. And with this split it's like building a metal bridge with one part of it made of rope.

  Joel Coehoorn : Only if the Regex is the rope.

  Cipher : get rid of the splits and use RegexOptions.Multiline

  Cipher : Also you have an extra backslash infront of the \d... should be @"^(\w+):\s+(\d+)$";

• Why don't you simply split by lines, then the text by ':' and trim the results? Or is it more complex issue?

  tomaszs : I would like to do this with Regex for future changes

  Miha Markic : I see. Then it has to be regex.

• Not having used C# I can't give a direct code sample.

  If it follows normal regex patterns though, the problem might be the ^/$.. normally that matches start of string (^) and end of string ($) not necessarily "end of line".

  What if you try something like (tested with perl):

  /(\w+):\s(\w+)(?:\r\n)?/g

• Here is a tested solution. ;)

  static void Main(string[] args)
  {
   try
   {
  
    string sInput;
  
    // The string to search.
    sInput = "ParameterINeed: 758\r\nParameterCount: 8695\r\nParameterText: 56";
  
  
    var regex = new Regex(@"(?<parameter>\w+):\s+(?<value>\d+)");
    var dictionary = new Dictionary<string, string>();
  
    foreach (Match match in regex.Matches(sInput))
    {
     dictionary.Add(
     match.Groups["parameter"].Value, 
     match.Groups["value"].Value); 
    }
  
    foreach (KeyValuePair<string, string> item in dictionary)
     Console.WriteLine("key: {0}; value:{1}", item.Key, item.Value);
  
   }
   finally
   {
    Console.ReadKey();
   }
  
  }
  

• The RegexOptions.SingleLine only affects how the period token works, not how the ^ and $ tokens work. You need to use RegexOptions.MultiLine for that.

  The multiline mode doesn't understand the \r\n line breaks, it only considers the \n character as line break. You have to consume the \r character to get to the line break.

  string text = "ParameterINeed: 758\r\nParameterCount: 8695\r\nParameterText: 56";
  string pattern = @"^(\w+):\s+(\d+)\r?$";
  MatchCollection ma = Regex.Matches(text, pattern, RegexOptions.Multiline);
  

  Now ma.Count is 3.

  This is how you put the matches in a dictionary:

  Dictionary<string, int> values = new Dictionary<string, int>();
  foreach (Match match in ma) {
   values.Add(match.Groups[1].Value, int.Parse(match.Groups[2].Value));
  }
  

  AnthonyWJones : SingleLine causes $ to match the end of the string. Where as Multiline causes $ to match the first new line.

  Guffa : @AnthonyWJones: No, SingleLine doesn't change how $ works at all, it only changes how the period works. Multiline causes $ to match the end of each line, not the new line character.

  Cipher : This is the correct answer.