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Read a CSV file with Regular Expressions in .Net

Greg — Tue, 23 Jun 2009 18:51:17 +0000

Here’s how you can read a CSV file using Regular Expressions in .Net:

p>
public static DataTable GetDataTableFromCsvFile(string file)
{
// Where the CSV data goes
DataTable dt = new DataTable("CsvData");

// The pattern used to parse the CSV
const string csvPattern = ",(?=(?:[^\"]*\"[^\"]*\")*(?![^\"]*\"))";
Regex csvRegex = new Regex(csvPattern);

// Read all lines in the file
// (not great for large files)
string[] fileLines = File.ReadAllLines(file);

// Get the column headers
// (assumes first row has headers and that
// each column contains string values and
// that each column name is unique)

Dictionary<int, string> headers = new Dictionary<int, string>();
string[] headerValues = csvRegex.Split(fileLines[0]);

for (int i = 0; i < headerValues.Length; i++)
{
headers.Add(i, headerValues[i]);
dt.Columns.Add(new DataColumn(headerValues[i], typeof (string)));
}

// Then add the the rest of the lines
for (int k = 1; k < fileLines.Length; k++)
{

DataRow dr = dt.NewRow();

string line = fileLines[k];
string[] cols = csvRegex.Split(line);

for (int i = 0; i < cols.Length; i++)
{
string header = headers[i];
string data = cols[i];

// remove quotes around the field
if (data.Length > 1 && data.StartsWith("\"") && data.EndsWith("\""))
data = data.Remove(data.Length - 1, 1).Remove(0, 1);

dr[header] = data;
}

dt.Rows.Add(dr);
}

return dt;
}

Of course, you will need to add in error catching and handling as well.

Hope this helps!

Regular Expression (RegEx) to Find Whole Words in a String

Greg — Thu, 31 Jul 2008 05:07:58 +0000

Ever want to match and replace whole words with in a string? Regular expressions (System.Text.RegularExpressions) makes it a one line operation:

Regex.Replace(inputText, @"\b" + wordToReplace + @"\b", replacementText, RegexOptions.IgnoreCase);

This pattern uses “word boundries” as your delimiters for matching text.

Regex to Clean Out HTML from Text

Greg — Thu, 18 Oct 2007 00:14:41 +0000

Ahh, the power (and sometimes slight confusion) of regular expressions. This seems to work well to remove HTML from text:

string htmlstring = { some chunk o html infested text };

Regex cleanOutHtml =
new Regex(@”\s]+))?)+\s*|\s*)/?>”);

string onlytext = cleanOutHtml.Replace(htmlstring, “”);

Weee there you have it.