CODEWITHSUNDEEP
c#asp.net-mvc
Matt Mitchell
Matt Mitchell

Reputation: 41823

Cannot use local variable before it is declared ASP.NET

I have some code like this:

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Save([Bind(Prefix="")]Person person)
{
    String s = person.property;
    /* ... */
}

But it throws the error: "Cannot use local variable 'person' before it is declared".

What simple thing am I missing?

Upvotes: 3

Views: 12009

Answers (3)

Frankie Lee
Frankie Lee

Reputation: 21

I had the same problem with a declared variable named endingYear.

Declared here:

        public ChartData(MetricInfo metricInfo, MetricItem[] metricItems) : this()
        {
            int endingYear = 0;

Further along in the method this was not a problem:

            endingYear = endingDate.Year;

But when I referenced the very same varable in a Case statement I got the "Cannot use local variable before it is declared" error even thou the variable was in intelesense:

                case "QRTR_LAST_FULL_QRTR":
                    if (metricInfo.CalendarType == "CALENDAR")
                    {
                        switch (endingDate.Month)
                        {
                            case 1:
                            case 2:
                            case 3:
                                loopControl = 4;
                                endingYear = endingDate.Year - 1;

Based on Matt's result I tried changing the variable name to endYear and the problem went away. Very strange and a waste of a half hour or so. If it was not for this thread of posts it probably would have been a bigger time loss.

Upvotes: 2

Stark Botha
Stark Botha

Reputation:

It is most likely that you are receiving this error because the same variable is being declared later in the same code block.

According to compiler rules, a variable reference will refer to default by a matching declaration withing the same block EVEN IF THE SAME DECLARATION EXISTS OUTSIDE OF THE BLOCK IN IN LOGICAL SCOPE FLOW.

So in short, check to see if the variable isnt being declared later on(a couple of lines down) in the same application block.

Upvotes: 16

Matt Mitchell
Matt Mitchell

Reputation: 41823

Okay, this is just some really bizarre error - if the variable is named a particular name it does not work, for any other name it does work...

Upvotes: 4

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