An example. To declare an enum type we use the enum keyword. The enumerated constants can be any identifier, and their actual values are automatically incremented.
Next In this program, the Priority.None enum will have value of 0. And the Priority.Critical enum will have value of 4.
Note The ToString virtual method will look into the assembly metadata to get the string value to return.
Tip The first enumerated constant in an enum should be a "None" or "Zero" value so it can be correctly tested against zero.
Finally We print the 5 string values in the enum. The GetNames method returns the same strings.
using System;
enum Priority
{
None,
Trivial,
Normal,
Important,
Critical
}
class Program
{
static void Main()
{
// Write string representation for Important.
Priority priorityValue = Priority.Important;
string enumValue = priorityValue.ToString();
// Loop through enumerations.// ... Write string representations.
Console.WriteLine("::FOR::");
for (Priority p = Priority.None; p <= Priority.Critical; p++)
{
string value = p.ToString();
Console.WriteLine(value);
}
Console.WriteLine("::GETVALUES::");
foreach (Priority p in Enum.GetValues(typeof(Priority)))
{
string value = p.ToString();
Console.WriteLine(value);
}
}
}::FOR::
None
Trivial
Normal
Important
Critical
::GETVALUES::
None
Trivial
Normal
Important
Critical
Reflection. The base.GetType() call, the GetValueField call, and InternalGetValue use reflection. They acquire the string representation from the enum constant from your source metadata.
Warning This has a performance impact. But it also reduces the complexity the source code—you do not need to store the strings yourself.
public override string ToString()
{
Type type = base.GetType();
object obj2 = ((RtFieldInfo)GetValueField(type))
.InternalGetValue(this, false);
return InternalFormat(type, obj2);
}
A discussion. There is a static Enum.GetNames method that receives one Type parameter in the Enum class. This method provides a clearer way to get an array of all of the enum strings.
Detail It is preferable to use the GetNames method instead of the for-loop construct as shown. There are drawbacks to both approaches.
A summary. ToString uses reflection. It returns an enum's string representation. We saw an example of the output of calling ToString on all values in an enumerated type.
Dot Net Perls is a collection of pages with code examples, which are updated to stay current. Programming is an art, and it can be learned from examples.
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This page was last updated on Nov 17, 2022 (simplify).