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

Question

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

Answer 1

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);
}

Answer 2

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);
}

Answer 3

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

Answer 4

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

Answer 5

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();
 }

}

Answer 6

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));
}