Parsing Strings to Boolean

If you don't need to check for other strings than True or False, then, you should use Boolean.Parse or Boolean.TryParse.

// Return true
Boolean.Parse("true");
// Return false
Boolean.Parse("false");
// Exception.. you can prevent that from happening by using a try..catch
// or using TryParse.
Boolean.Parse("foo");

bool isBool;
if(Boolean.TryParse("true", out isBool))
{
  // If we get in here, we know that isBool is a valid boolean, 
  // either "True" or "False".
}

bool isBool2;
if(Boolean.TryParse("foo", out isBool2))
{
  //We won't get in here because "foo" isn't a boolean.
}

Otherwise, I'd use this modified version of TryParse. If the result isn't True, or False, the method will return False. If the result is found, the method will return True. The result can be found in the out parameter.

private static readonly List<string> TrueString = new List<string>(new string[]{"true", "t", "1", "yes", "y"});

private static readonly List<string> FalseString = new List<string>(new string[]{"false", "f", "0", "no", "n"});

public static bool TryConvertToBoolean(string input, out bool result)
{
  // Remove whitespace from string and lowercase
  string formattedInput = input.Trim().ToLower();
  
  if(TrueString.Contains(formattedInput))
  {
    result = true;
    return true;
  }
  else if (FalseString.Contains(formattedInput))
  {
    result = false;
    return true;
  }
  else
  {
    result = false;
    return false;
  }
}

*UPDATE* The code now compile. Sorry, I hadn't tested.