#970 – Checking for Valid Characters in a String

You can use a regular expression to check a string to see if the string contains only characters within a specified set of characters.

For example, to check whether a string is limited to a single line containing only alphabetic characters (e.g. a..z, A..Z), you can use the regular expression shown below.

        private bool IsAlphabetic(string s)
        {
            Regex r = new Regex(@"^[a-zA-Z]+$");

            return r.IsMatch(s);
        }

The regular expression defines a pattern and the IsMatch method checks the string to see if it matches the pattern.  You can read the regular expression as follows:

  • ^ – start of the string
  • [a..zA..Z] – single character that is a lowercase or uppercase letter
  • + – repeat previous item one or more times (alphabetic character)
  • $ – end of the string

A string will therefore match if it is a single line of text containing at least one alphabetic character and is limited to alphabetic characters.

946-001

946-002

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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

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