What is the most appropriate way to compare a string to a stringable object by value?

Question

With this:

if (args.Parameter == "ContactIntermediaryPage")

...in a NavigatedTo() event handler, Resharper tells me: "Possible unintended reference comparison; to get a value comparison, cast the left hand side to type 'string'"

So should I change it to one of the following, and, if so, which one:

if ((string)args.Parameter == "ContactIntermediaryPage")

if (args.Parameter.ToString() == "ContactIntermediaryPage")

if (args.Parameter.Equals("ContactIntermediaryPage"))

Is there any concern for the `null` case where `args.Parameter` is null? That can _definitely_ have a significant impact depending on which option you use. — Chris Sinclair, Dec 17 '12 at 22:33
`if (args.Parameter.Equals("ContactIntermediaryPage"))` would not work - since it expects an object of type `Parameter` — Matt Roberts, Dec 17 '12 at 22:42

score 2 · Answer 1 · answered Dec 17 '12 at 22:27

2

I would choose third one, making it also case insensitive (if this is suitable in your case)

if (args.Parameter.ToString().Equals(
               "ContactIntermediaryPage", 
                StringComparsion.InvariantCultureIgnoreCase))

In other words, if you're comparing to a string make left part of equation a string, to make clear to a compiler and to a reader of your code, what you're going to do on that line.

answered Dec 17 '12 at 22:27

Tigran

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Prb stating the obvious, but just to add that you don't need the `InvariantCultureIgnoreCase` if you do care about case (it's always going to be in CamelCase. – Matt Roberts Dec 17 '12 at 22:49

score 1 · Accepted Answer · answered Dec 17 '12 at 22:32

the first one if args.Parameter is always a string. It saves an extra call.

otherwise the second one if, and only if, all possible strings are within your code. If so, I would define the strings as constants and reference them in one place if possible.

If neither of the above are true, then go for Tigran's answer.

What is the most appropriate way to compare a string to a stringable object by value?

2 Answers2