CODEWITHSUNDEEP
c#
Alan2
Alan2

Reputation: 24572

How can I parse a value that appears some place in a file using C#

I have strings and each contain a value of RowKey stored like this:

data-RowKey=029

This occurs only once in each file. Is there some way I can get the number out with a C# function or do I have to write some kind of select myself. I have a team mate who suggested linq but I'm not sure if this even works on strings and I don't know how I could use this.

Update:

Sorry I changed this from file to string.

Upvotes: 0

Views: 62

Answers (4)

Tim Schmelter
Tim Schmelter

Reputation: 460158

Assuming that it only exists once in a file, i would even throw an exception otherwise:

String rowKey = null;
try
{
    rowKey = File.ReadLines(path)
                .Where(l => l.IndexOf("data-RowKey=") > -1)
                .Select(l => l.Substring(12 + l.IndexOf("data-RowKey=")))
                .Single();
}
catch (InvalidOperationException) {
    // you might want to log this exception instead
    throw;
}

Edit: The simple approach with a string, take the first occurence which is always of length 3:

rowKey = text.Substring(12 + text.IndexOf("data-RowKey="), 3);

Upvotes: 1

Stefan
Stefan

Reputation: 14880

Linq does not really help you here. Use a regular expression to extract the number:

data-Rowkey=(\d+)

Update:

Regex r = new Regex(@"data-Rowkey=(\d+)");

string abc =  //;
Match match = r.Match(abc);
if (match.Success) 
{
  string rowKey = match.Groups[1].Value;
}

Code:

public string ExtractRowKey(string filePath)
{
  Regex r = new Regex(@"data-Rowkey=(\d+)");

  using (StreamReader reader = new StreamReader(filePath))
  {
    string line; 
    while ((line = reader.ReadLine()) != null)
    {
      Match match = r.Match(line);
      if (match.Success) return match.Groups[1].Value;
    }
  }
}

Upvotes: 2

David Brabant
David Brabant

Reputation: 43499

Regex g = new Regex(@"data-RowKey=(?<Value>\d+)");

using (StreamReader r = new StreamReader("myFile.txt"))
{
    string line;
    while ((line = r.ReadLine()) != null)
    {
        Match m = g.Match(line);
        if (m.Success)
        {
            string v = m.Groups["Value"].Value;
            // ...
        }
    }
}

Upvotes: 1

Tilak
Tilak

Reputation: 30708

Assuming following

  1. File must contain data-Row (with exact match including case)
  2. Number length is 3

Following is the code snippet

        var fileNames = Directory.GetFiles("rootDirPath");

        var tuples = new List<Tuple<String, int>>();
        foreach(String fileName in fileNames)
        {
            String fileData =File.ReadAllText(fileName) ;
            int index = fileData.IndexOf("data-RowKey=");
            if(index >=0)
            {
                String numberStr = fileData.Substring(index+12,3);// ASSUMING data-RowKey is always found, and number length is always 3
                int number = 0;
                int.TryParse(numberStr, out number);
                tuples.Add(Tuple.Create(fileName, number));
            }
        }

Upvotes: 1

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