[c#] Get Substring - everything before certain char

I'm trying to figure out the best way to get everything before the - character in a string. Some example strings are below. The length of the string before - varies and can be any length

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

so I need the value that's from the start index of 0 to right before -. So the substrings would turn out to be 223232, 443, and 34443553

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

One way to do this is to use String.Substring together 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 up to, but not including, the dash.

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;
    }

The LINQy way

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

(But, you do need to test for null ;)

You can use regular expressions for this purpose, but it's good to avoid extra exceptions when input string mismatches against regular expression.

First to avoid extra headache of escaping to regex pattern - we could just use function for that purpose:

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

I know that this does not do anything - as "-" is the same as Regex.Escape("=") == "=", but it will make difference for example if character is @"\".

Then we need to match from begging of the string to string ending, or alternately if ending is not found - then match nothing. (Empty string)

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

If your application is performance critical - then separate line for new Regex, if not - you can have everything in one line.

And finally match against string and extract matched pattern:

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

And after that you can either write separate function, like it was done in another answer, or write inline lambda function. I've wrote now using both notations - inline lambda function (does not allow default parameter) or 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());
    }
}

Btw - changing regex pattern to "^(.*?)(-|$)" will allow to pick up either until "-" pattern or if pattern was not found - pick up everything until end of string.

Things have moved on a bit since this thread started.

Now, you could use

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

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 string doesn't have a - then you'll get the whole string.