CODEWITHSUNDEEP
c#asp.net-mvcasp.net-mvc-3entity-framework-4
user522767
user522767

Reputation: 4033

why converting or parsing string to int return zero?

Why converting / parsing string to int return 0 / zero?

On debug, using the breakpoint, I could see "3" posted to browse action as a string value but when i convert to int as above, the value is converted to 0 value of int type.

    //
    // GET: /Event/Browse
    public ActionResult Browse(string category)
    {
        int id = Convert.ToInt32(category);


        // Retrieve Category and its Associated Events from database
        var categoryModel = storeDB.Categories.Include("Events").Single(g => g.CategoryId == id);
        return View(categoryModel);
    }

Take a look at the image below for better understanding: enter image description here

Another image - categoryModel getting null on LINQ query. enter image description here

Upvotes: 2

Views: 4472

Answers (2)

jonsca
jonsca

Reputation: 10381

From MSDN on Int32.TryParse here

When this method returns, contains the 32-bit signed integer value equivalent to the number contained in s, if the conversion succeeded, or zero if the conversion failed. The conversion fails if the s parameter is nullptr, is not of the correct format, or represents a number less than MinValue or greater than MaxValue. This parameter is passed uninitialized.

Upvotes: 5

Kon
Kon

Reputation: 27441

If your Parse() call fails and your exception is uncaught or you don't test the return value of TryParse(), then surely the int variable would remain as it was - initialized by default to zero.

For example, this would keep your int a zero: 

int i;
Int32.Parse("FAIL!");
// i is still a zero.

So instead try this: 

int i;
bool parseSuccessful = Int32.TryParse("123", out i);
// parseSuccessful should be true, and i should be 123.

Or to see it fail gracefully:

int i;
bool parseSuccessful = Int32.TryParse("FAIL!", out i);
// parseSuccessful should be false, and i should be 0.

Upvotes: 4

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