string
is an alias in C# for System.String
.
So technically, there is no difference. It's like int
vs. System.Int32
.
As far as guidelines, it's generally recommended to use string
any time you're referring to an object.
e.g.
string place = "world";
Likewise, I think it's generally recommended to use String
if you need to refer specifically to the class.
e.g.
string greet = String.Format("Hello {0}!", place);
This is the style that Microsoft tends to use in their examples.
It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.
In .NET Core and .NET Framework ≥4.0 there is a generic parse method:
Enum.TryParse("Active", out StatusEnum myStatus);
This also includes C#7's new inline out
variables, so this does the try-parse, conversion to the explicit enum type and initialises+populates the myStatus
variable.
If you have access to C#7 and the latest .NET this is the best way.
Original Answer
In .NET it's rather ugly (until 4 or above):
StatusEnum MyStatus = (StatusEnum) Enum.Parse(typeof(StatusEnum), "Active", true);
I tend to simplify this with:
public static T ParseEnum<T>(string value)
{
return (T) Enum.Parse(typeof(T), value, true);
}
Then I can do:
StatusEnum MyStatus = EnumUtil.ParseEnum<StatusEnum>("Active");
One option suggested in the comments is to add an extension, which is simple enough:
public static T ToEnum<T>(this string value)
{
return (T) Enum.Parse(typeof(T), value, true);
}
StatusEnum MyStatus = "Active".ToEnum<StatusEnum>();
Finally, you may want to have a default enum to use if the string cannot be parsed:
public static T ToEnum<T>(this string value, T defaultValue)
{
if (string.IsNullOrEmpty(value))
{
return defaultValue;
}
T result;
return Enum.TryParse<T>(value, true, out result) ? result : defaultValue;
}
Which makes this the call:
StatusEnum MyStatus = "Active".ToEnum(StatusEnum.None);
However, I would be careful adding an extension method like this to string
as (without namespace control) it will appear on all instances of string
whether they hold an enum or not (so 1234.ToString().ToEnum(StatusEnum.None)
would be valid but nonsensical) . It's often be best to avoid cluttering Microsoft's core classes with extra methods that only apply in very specific contexts unless your entire development team has a very good understanding of what those extensions do.
Best Answer
Update As of C# 7:
or if you don't need the number you can discard the out parameter
The var s can be replaced by their respective types!