Retrieving substring from a string

static string ExtractCompany(string source) {
   int bra = source.IndexOf('[');
   int ket = source.IndexOf(']');
   return source.Substring(bra, ket - bra - 1);
}

using Regex = System.Text.RegularExpressions.Regex;

//...

static string ExtractCompany(string source) {
    string pattern = @"\[.*\]";
    Regex regex = new Regex(pattern);
    var matches = regex.Matches(source);
    if (matches.Count < 1) return; //for example
    return matches[0].Value.Trim(new char[] { '[', ']' });
}

s.Substring(s.IndexOf("[") + 1, s.IndexOf("]") - s.IndexOf("[") - 1)

public static string ExtractCompanyName(string data)
{
return(data.Substring(data.IndexOf("[")+1, data.Length-2 - data.IndexOf("[")));
}