I am new to C# and I am using windows forms. I am dealing with Postcodes string and I am trying to get the first letters from the Post code and store it in a variable, for example:
BL9 8NS (I want to get BL)
L8 6HN (I want to get L)
CH43 7TA (I want to get CH)
WA8 7LX (I want to get WA)
I just want to get the first letters before the number and as you can see the number of letters can be 1 or 2 and maybe 3. Anyone knows how to do it? Thank you
Since string imlements IEnumerable<char>, using Linq TakeWhile and char.IsLetter would be very easy:
string firstLetters = string.Concat(str.TakeWhile(char.IsLetter)); Use a regex with a group to match the first letters.
This is the regex you need:
^([a-zA-Z]+) You can use it like this:
Regex.Match("BL9 8NS", "^([a-zA-Z]+)").Groups[1].Value The above expression will evaluate to "BL".
Remember to add a using directive to System.Text.RegularExpressions!
You can use StringBuilder and loop through the characters until the first non-letter.
string text = "BL9 8NS"; StringBuilder sb = new StringBuilder(); foreach(char c in text) { if(!char.IsLetter(c)) { break; } sb.Append(c); } string result = sb.ToString(); // BL Or if you don't care about performance and just want it simple, you can use TakeWhile:
string result = new string(text.TakeWhile(c => char.IsLetter(c)).ToArray()); 
string is immutable and so we wouldn't want to create 1000 new reference type objects on the stack.What about
string result = postcode.Substring(0, postcode.IndexOf(postcode.First(Char.IsDigit))); If your postcodes will always contain that digit, First won't throw any exception.
postcode.First(!Char.IsLetter) ?FirstOrDefault won't thow an exception if you're worried about that.
Substring will in that case (with FirstOrDefault)char[] numbers = new char[]{ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' }; string a = "BL9 8NS"; string result = a.Substring( 0, a.IndexOfAny(numbers) ); Console.WriteLine( result ); 
While the answer of Ofir Winegarten is really great, I up-voted it, I wanted to share my answer I wrote before the sudden power cut!
string code = "BL9 8NS"; string myStr = ""; for (int i = 0; i < code.Length; i++) { if (char.IsNumber(code[i])) break; else myStr += code[i]; } 
int.TryParse(code[i].ToString(), out int _n) - just NO-NO-NO! In .Net you can use char.IsXXX() methods, where XXX - is one of the Unicode categories. char.IsDigit() is one of them. It is much faster and easier to read