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.
1 2 3 4 5 6 | 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.
