how to get a's in string c# code example

Example: c# substring find word

public static string GetSubstring(string l_Source, string l_FindCharacter)
  {
    if (!l_Source.Contains(l_FindCharacter)) return string.Empty;
    int End = l_Source.IndexOf(l_FindCharacter, 0) + l_FindCharacter.Length;
    return l_Source.Substring(0, End - 1);
  }
//string l_Data = GetSubstring("100000.00", "."); //Test //100000