将字符串解析为枚举类型

Question

我有一个像这样的枚举类型作为例子:

public Enum MyEnum {
    enum1, enum2, enum3 };

我将从配置文件中读取一个字符串.我需要它来解析字符串到MyEnum类型或null o未定义.不确定以下代码是否有效(对不起现在无法访问我的VS):

// example: ParseEnum<MyEnum>("ENUM1", ref eVal);
bool ParseEnum<T>(string value1, ref eVal) where T : Enum
{
  bool bRet = false;
  var x = from x in Enum.GetNames(typeof(T)) where 
       string.Equals(value1, x, StringComparison. OrdinalIgnoreCase)
       select x;
  if (x.Count() == 1 )
  {
    eVal = Enum.Parse(typeof(T), x.Item(0)) as T;
    bRet = true;
  }
  return bRet;
}

不确定它是否正确或有任何其他简单的方法将字符串解析为MyEnum值？

Answer 1

怎么样的:

public static class EnumUtils
{
    public static Nullable<T> Parse<T>(string input) where T : struct
    {
        //since we cant do a generic type constraint
        if (!typeof(T).IsEnum)
        {
            throw new ArgumentException("Generic Type 'T' must be an Enum");
        }
        if (!string.IsNullOrEmpty(input))
        {
            if (Enum.GetNames(typeof(T)).Any(
                  e => e.Trim().ToUpperInvariant() == input.Trim().ToUpperInvariant()))
            {
                return (T)Enum.Parse(typeof(T), input, true);
            }
        }
        return null;
    }
}

用作:

MyEnum? value = EnumUtils.Parse<MyEnum>("foo");

(注:旧版本try/catch左右使用Enum.Parse)

Answer 2

private enum MyEnum
{
    Enum1 = 1, Enum2 = 2, Enum3 = 3, Enum4 = 4, Enum5 = 5, Enum6 = 6, 
    Enum7 = 7, Enum8 = 8, Enum9 = 9, Enum10 = 10
}

private static Object ParseEnum<T>(string s)
{
    try
    {
        var o = Enum.Parse(typeof (T), s);
        return (T)o;
    }
    catch(ArgumentException)
    {
        return null;
    }
}

static void Main(string[] args)
{
   Console.WriteLine(ParseEnum<MyEnum>("Enum11"));
   Console.WriteLine(ParseEnum<MyEnum>("Enum1"));
   Console.WriteLine(ParseEnum<MyEnum>("Enum6").GetType());
   Console.WriteLine(ParseEnum<MyEnum>("Enum10"));
}

OUTPUT:

    //This line is empty as Enum11 is not there and function returns a null
Enum1
TestApp.Program+MyEnum
Enum10
Press any key to continue . . .