How do you remove all the alphabetic characters from a string?

I have a string containg alphabetic characters, for example:

1. 254.69 meters
2. 26.56 cm
3. 23.36 inches
4. 100.85 ft

I want to remove all the alphabetic characters (units) from the above mentioned strings so that I can call the double.Parse() method.

This should work:

// add directive at the top 
using System.Text.RegularExpressions;

string numberOnly = Regex.Replace(s, "[^0-9.]", "")

You should be able to solve this using Regex. Add the following reference to your project:

using System.Text.RegularExpressions;

after that you can use the following:

string value = Regex.Replace(<yourString>, "[A-Za-z ]", "");
double parsedValue = double.Parse(value);

Assuming you have only alphabetic characters and space as units.

Using LINQ:

using System.Linq;
    
string input ="57.20000 KG ";
string output = new string(input.Where(c=>(Char.IsDigit(c)||c=='.'||c==',')).ToArray());

The Regex, and Vlad's LINQ answers cover the solution well. And are both good options.

I had a similar problem, but I also wanted to only explicitly strip letters, and not to strip white space or etc, with this variant.

I also wanted it usable as below. Any of the other solutions could be packaged in a similar manner.

public static string StripAlpha(this string self)
{
    return new string( self.Where(c => !Char.IsLetter(c)).ToArray() );
}

public static string StripNonNumeric(this string self)
{
    // Use Vlad's LINQ or the Regex Example
    return new string(self.Where(c=>(Char.IsDigit(c)||c=='.'||c==',')).ToArray()) ;  // See Vlad's

}

This would then be used such as:

var newString = someString.StripAlpha();
var newString2 = someString.StripNonNumeric();

Hi another solution is:

// add directive at the top 
using System.Text.RegularExpressions;
string s = "24,99";
string numberOnly = Regex.Replace(s, "[^0-9,-]+", "")

This solution will not remove the dot e.g. question from user1804084:

this remove the dot for me e.g. 24.99 somechracter -> 2499

However it can still be convertet to a double where adding and subtraction works as normal.

Use CharMatcher API from Google's Guava library:

String magnitudeWithUnit = "254.69 meter";
String magnitude = CharMatcher.inRange('a', 'z').or(inRange('A', 'Z')).removeFrom(magnitudeWithUnit);

Do static-import CharMatcher.inRange(..). You can trim the results for trailing space.