Enum.TryParse returns true for any numeric values

user_554045 0
Viewed 14165

I'm running into a behavior I wasn't expecting when using Enum.TryParse.

If I have an enum:

public enum MyEnum
{
  ValueA,
  ValueB,
  ValueC
}

And then I pass a numeric value (as a string) into Enum.TryParse, like:

MyEnum outputEnum;
bool result = Enum.TryParse("1234", out outputEnum);

Despite the string "1234" not being a possible value, result will come back as true, and my outputEnum will have a value of 1234.

Is there a way I can avoid this sort of behavior? I'm trying to write a function which will process arbitrary string input as an enum, and this has thrown a bit of a monkeywrench in my bad-input detection.

tryparse validation enums c#
3 Answers

Use it like this

bool result = Enum.TryParse("1234", out MyEnum outputEnum) && Enum.IsDefined(typeof(MyEnum), outputEnum);

The value of result will be false but the value of outputEnum is still 1234

user_27284660

If you want to avoid numeric values being accepted entirely and want to avoid Enum.IsDefined(), you can add a check to the condition to verify that the string is not numeric. There's a bunch of different ways to do that with different trade-offs but, for example you could do this:

string valueToParse = "1234";
bool result = !valueToParse.All(char.IsDigit) && Enum.TryParse(valueToParse, out MyEnum outputEnum);
user_15060860
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