Extract Hex Digits From a String
By
Steve on
Tuesday, January 09, 2007
Updated
Friday, April 22, 2016
Viewed
24,527 times. (
9 times today.)
Summary
This is a simple little routine that uses the .NET Regex class to extract
only the hex digits from an input string (0-9, A-F). Since hex digits
or colors in string form may often be preceded by other characters
such as 'x' or '#' this method allows you to easily standardize
the format of the hex string.
Extracting Hex Digits
// Add this method to an ASP.NET page with a Label control lblOutput.
public void TestExtractHexDigits()
{
// invent a few hex string with extra characters
string[] hex = new string[3];
hex[0] = "#FFFFFF";
hex[1] = "xAE";
hex[2] = "'7AEAEAEAE'H";
// extract the hex digits and write to web page
lblOutput.Text = "";
foreach (string h in hex)
lblOutput.Text
+= h + " -> " + Snippets00003.ExtractHexDigits(h) + "<br>";
}
If you run the previous method you'll get the following output:
Example: Output
#FFFFFF -> FFFFFF
xAE -> AE
'7AEAEAEAE'H -> 7AEAEAEAE
namespace Cambia.CoreLib
{
using System;
using System.Text.RegularExpressions;
/// <summary>
/// Useful C# snippets from CambiaResearch.com
/// </summary>
public class Snippets00003
{
public Snippets00003()
{
}
/// <summary>
/// Extract only the hex digits from a string.
/// </summary>
public static string ExtractHexDigits(string input)
{
// remove any characters that are not digits (like #)
Regex isHexDigit
= new Regex("[abcdefABCDEF\\d]+", RegexOptions.Compiled);
string newnum = "";
foreach (char c in input)
{
if (isHexDigit.IsMatch(c.ToString()))
newnum += c.ToString();
}
return newnum;
}
}
}