Enum.Parse does not trigger exception when expected

Question

Say that I have this Enum:

enum GradeEnum
{
    A = 1,
    B = 2,
    C = 3,
}

Then I do

GradeEnum grade = (GradeEnum)Enum.Parse(typeof(GradeEnum),"234");

Then there no error triggered and the grade variable value is 234. But if I do comparaison with value of GradeEnum as expected the grade variable has not matched value.

Question, why is there no exception trigger by the Parse method?

That's how enums work, you can give them any value you like, they're really just `int` (most of the time) — DavidG, Aug 25 '17 at 14:22
Even stranger is: `enum GradeEnum{ A = 1, B = 2, C = 3} ... GradeEnum g = (GradeEnum) 4;` — Tim Schmelter, Aug 25 '17 at 14:45

M.kazem Akhgary · Accepted Answer · 2017-08-25T14:31:58.483

5

You should use Enum.IsDefined to check whether enum is defined or not.

In order to parse and also validate you need both methods.

GradeEnum grade = (GradeEnum)Enum.Parse(typeof(GradeEnum), "234");
if (!Enum.IsDefined(typeof(GradeEnum), grade))
    ; // throw exception

Or use TryParse mentioned in comment bellow, forgot that!

string gradeValue = "234";
GradeEnum grade;
if (Enum.TryParse(gradeValue, out grade))
{
    // success
}

edited Aug 25 '17 at 14:31

answered Aug 25 '17 at 14:23

M.kazem Akhgary

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1

Ok, why not `Enum.TryParse`? – Tim Schmelter Aug 25 '17 at 14:26
1

This doesn't answer the question: _" why is there no exception trigger by the Parse method?"_ But it was already answered [here](https://stackoverflow.com/questions/6741649/enum-tryparse-returns-true-for-any-numeric-values) – Tim Schmelter Aug 25 '17 at 14:28

Enum.Parse does not trigger exception when expected

1 Answers1