Get Substring - all up to a specific char

Question

I am trying to find the best way to get everything up to a character in a string. Below are some sample strings. The length of the line to - varies and can be any length

223232-1.jpg 443-2.jpg 34443553-5.jpg 

so I need a value that is from the starting index from 0 to the right -. Thus, the substrings would be 223232, 443, and 34443553

Answer 1

Net Fiddle Example

 class Program { static void Main(string[] args) { Console.WriteLine("223232-1.jpg".GetUntilOrEmpty()); Console.WriteLine("443-2.jpg".GetUntilOrEmpty()); Console.WriteLine("34443553-5.jpg".GetUntilOrEmpty()); Console.ReadKey(); } } static class Helper { public static string GetUntilOrEmpty(this string text, string stopAt = "-") { if (!String.IsNullOrWhiteSpace(text)) { int charLocation = text.IndexOf(stopAt, StringComparison.Ordinal); if (charLocation > 0) { return text.Substring(0, charLocation); } } return String.Empty; } } 

Answer 2

Use the split function.

 static void Main(string[] args) { string s = "223232-1.jpg"; Console.WriteLine(s.Split('-')[0]); s = "443-2.jpg"; Console.WriteLine(s.Split('-')[0]); s = "34443553-5.jpg"; Console.WriteLine(s.Split('-')[0]); Console.ReadKey(); } 

If your line does not have - , you will get the whole line.

Answer 3

 String str = "223232-1.jpg" int index = str.IndexOf('-'); if(index > 0) { return str.Substring(0, index) } 

Answer 4

Things have moved a little since the beginning of this stream.

Now you can use

 string.Concat(s.TakeWhile((c) => c != '-')); 

Answer 5

One way to do this is to use String.Substring along with String.IndexOf :

 int index = str.IndexOf('-'); string sub; if (index >= 0) { sub = str.Substring(0, index); } else { sub = ... // handle strings without the dash } 

Starting at position 0, return all text to, but not including a dash.

Answer 6

Building on BrainCore's answer:

  int index = 0; str = "223232-1.jpg"; //Assuming we trust str isn't null if (str.Contains('-') == "true") { int index = str.IndexOf('-'); } if(index > 0) { return str.Substring(0, index); } else { return str; } 

Answer 7

You can use regular expressions for this purpose, but it is good to avoid additional exceptions when the input string does not match the regular expression.

Firstly, in order to avoid additional headaches when switching to the regular expression pattern, we could simply use the function for this purpose:

 String reStrEnding = Regex.Escape("-"); 

I know that this does nothing - since "-" is the same as Regex.Escape("=") == "=" , but it will make a difference, for example, if the @"\" character .

Then we need to match from the beginning of the line to the end of the line or, alternatively, if the end is not found, then nothing is found. (Blank line)

 Regex re = new Regex("^(.*?)" + reStrEnding); 

If your application is performance critical, then select a new line for the new Regex, if not, everything can be on one line.

Finally, match the string and extract the appropriate pattern:

 String matched = re.Match(str).Groups[1].ToString(); 

And after that you can write a separate function, as it was done in another answer, or write a built-in lambda function. I wrote now using both notations - the built-in lambda function (does not allow the default parameter) or a separate function call.

 using System; using System.Text.RegularExpressions; static class Helper { public static string GetUntilOrEmpty(this string text, string stopAt = "-") { return new Regex("^(.*?)" + Regex.Escape(stopAt)).Match(text).Groups[1].Value; } } class Program { static void Main(string[] args) { Regex re = new Regex("^(.*?)-"); Func<String, String> untilSlash = (s) => { return re.Match(s).Groups[1].ToString(); }; Console.WriteLine(untilSlash("223232-1.jpg")); Console.WriteLine(untilSlash("443-2.jpg")); Console.WriteLine(untilSlash("34443553-5.jpg")); Console.WriteLine(untilSlash("noEnding(will result in empty string)")); Console.WriteLine(untilSlash("")); // Throws exception: Console.WriteLine(untilSlash(null)); Console.WriteLine("443-2.jpg".GetUntilOrEmpty()); } } 

By the way, changing the regular expression pattern to "^(.*?)(-|$)" will allow you to select the pattern before "-" or, if the pattern was not found, collect everything to the end of the line.

Answer 8

LINQy way

String.Concat ("223232-1.jpg" .TakeWhile (c => c! = '-'))

(But you need to check for zero;)