TryParse in .net 3.5

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Hi all,

Please see below ASP.NET 4.5 code

C#

 if ( !Enum.TryParse( request.QueryString["q"], out cp.QuietZones ) )
cp.QuietZones = QuietZoneModules.Two;

I want corresponding 3.5 code. Enum.TryParse() is not in 3.5. Please help me.

thanks in advance,
Manu V Nath

Posted 4-Jun-13 2:42am

Manu V Nath

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5 solutions

Solution 2

Please try this link
http://damieng.com/blog/2010/10/17/enums-better-syntax-improved-performance-and-tryparse-in-net-3-5[^]

Hope this helps

Posted 4-Jun-13 2:52am

Jameel VM

Solution 1

http://damieng.com/blog/2010/10/17/enums-better-syntax-improved-performance-and-tryparse-in-net-3-5[^]

Posted 4-Jun-13 2:52am

bbirajdar

Solution 5

Try a switch, something like this:

switch(cp.QuietZone)
{
    case "one":
      zone = QuietZoneModules.One;
      break;
    case "two":
      zone = QuietZoneModules.Two;
      break;
    case "three":
      zone = QuietZoneModules.Three;
      break;
    default:
      zone = QuietZoneModules.Two;
}

Or use a constant dictionary to look it up, using something like this:

Dictionary<string,> zone = new Dictionary<string,> = {
      {"one",QuietZoneModules.One}, {"def",QuietZoneModules.Two}, {"ghi",QuietZoneModules.Three}
    };

Good luck!

Posted 4-Jun-13 3:03am

E.F. Nijboer

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JitendraSahu · Accepted Answer · 2013-06-04T03:01:00

TryParse has the following signature:

C#

ryParse<tenum>(string value, bool ignoreCase, out TEnum result)
    where TEnum : struct, new()
</tenum>

It has a generic type parameter

C#

TEnum

that must be a

C#

struct

and that it uses to determine the type of

C#

enum

that it is parsing. When you don't provide it explicitly (as you did), it will take the type of the resultInputType variable, which is Enum (and not the type of the enumeration itself). Note that

C#

Enum

is a class (even tough it inherits from ValueType) and therefore it does not satisfy the requirement that

C#

TEnum

is a

C#

struct

.

You can solve this by giving the method a generic argument instead of a Type parameter. The generic type parameter

C#

TEnum

must have the same constraints (i.e. struct) as the same parameter on the TryParse function. Otherwise you could put a class in the method while

C#

TryParse

does not accept that.

So try this:

C#

private static TEnum getEnumStringEnumType<tenum>()
    where TEnum : struct
{
    string userInputString = string.Empty;
    TEnum resultInputType = default(TEnum);
    bool enumParseResult = false;

    while (!enumParseResult)
    {                
        userInputString = System.Console.ReadLine();
        enumParseResult = Enum.TryParse(userInputString, true, out resultInputType);
    }
    return resultInputType;
}
</tenum>

To call the method, use:

C#

getEnumStringEnumType<myenum>();</myenum>

Ahmed Bensaid · Accepted Answer · 2013-06-04T02:54:00

Hello,

As seen on StackOverFlow :

C#

public static bool EnumTryParse<T>(string strType,out T result)
{
    string strTypeFixed = strType.Replace(' ', '_');
    if (Enum.IsDefined(typeof(T), strTypeFixed))
    {
        result = (T)Enum.Parse(typeof(T), strTypeFixed, true);
        return true;
    }
    else
    {
        foreach (string value in Enum.GetNames(typeof(T)))
        {
            if (value.Equals(strTypeFixed, StringComparison.OrdinalIgnoreCase))
            {
                result = (T)Enum.Parse(typeof(T), value);
                return true;
            }
        }
        result = default(T);
        return false;
    }
}