While using these methods I found a shortcoming... there is no support for flags! So this is how I improved it:

public static bool TryParseEnum(object value, out EnumType result)
{
result = default(EnumType);
if (value == null) return false;
var type = typeof (EnumType);
if (!type.IsEnum) return false;
int iValue;
return Int32.TryParse(value.ToString(), out iValue)
? TryParseEnum(iValue, out result)
: TryParseEnum(value.ToString(), out result);
}

public static bool TryParseEnum(int value, out EnumType result)
{
result = default(EnumType);
var type = typeof(EnumType);
if (!type.IsEnum) return false;
result = (EnumType)Enum.Parse(type, value.ToString());
// Verify if the result is valid,
// Enum.Parse might just return the input value, while this is not a defined value of the enum
if (result.ToString().Contains(", ") || Enum.IsDefined(type, result))
return true;
result = default(EnumType);
return false;
}

public static bool TryParseEnum(string value, out EnumType result)
{
result = default(EnumType);
if (string.IsNullOrEmpty(value)) return false;
var type = typeof(EnumType);
if (!type.IsEnum) return false;
value = value.ToUpperInvariant();
try
{
result = (EnumType)Enum.Parse(type, value, true);
return true;
}
catch (ArgumentException)
{
return false;
}
}

:edited: Edited the object method to use the two other methods, this should be more reliable for both normal enums and bit flag enums. Casting/parsing values which are non-numeric and non-string values is anyway not possible in .NET.

modified on Wednesday, February 10, 2010 6:31 AM

Why all the fuss about "starting programming a long time ago before the many of the rest of us"? I've been programming for 2 years now, and I wrote the folowing code snippit about one year ago:

public static bool TryParseEnum<TEnum>(int value, out TEnum result)
{
  result = default(TEnum);
  var type = typeof (TEnum);
  if (!type.IsEnum) return false;
  try
  {
    result = (TEnum) Enum.ToObject(type, value);
    return true;
  }
  catch
  {
    return false;
  }
}

public static bool TryParseEnum<TEnum>(string value, out TEnum result)
{
  result = default(TEnum);
  var type = typeof(TEnum);
  if (!type.IsEnum) return false;
  value = value.ToUpperInvariant();
  var names = Enum.GetNames(type);
  // Enum.IsDefined() is only available as case sensitive
  foreach (var name in names)
  {
    if (name.ToUpperInvariant() != value)
      continue;
    result = (TEnum)Enum.Parse(type, value, true);
    return true;
  }
  return false;
}

Advantages of this code: - you know if parsing succeeded (while you can't know when returning default values) - case insensitive

modified on Thursday, December 3, 2009 3:13 PM