CODEWITHSUNDEEP
c#windows-phone-8
Mohamed Thaufeeq
Mohamed Thaufeeq

Reputation: 1677

If condition error?

I have made a condition that if variable is null. But still this code breaks the app because of null variable.

CODE:

var page = IsolatedStorageSettings.ApplicationSettings["qsPage"];
var hash = IsolatedStorageSettings.ApplicationSettings["Ayath"];
if (page == null && hash == null)
// or if i use if (page == null || hash == null)
{    
MessageBox.Show("No Bookmark has been saved !");
}
else
{
NavigationService.Navigate(new Uri("/myWeb.xaml?Page=" + page + "&id=" + hash, UriKind.Relative));
}

Upvotes: 0

Views: 106

Answers (3)

Josue Yeray
Josue Yeray

Reputation: 1163

Using && in the if condition, the page can be null but the hash no, so it go to the else clausule and, as the page is null, it fail.

Try replacing && for || This way, everytime page OR hash is null, it show the message box.

Updated: As the page and hash variables are string, you need to test them using String.IsNullOrWhiteSpace, This way:

var page = IsolatedStorageSettings.ApplicationSettings["qsPage"];
var hash = IsolatedStorageSettings.ApplicationSettings["Ayath"];
if (string.IsNullOrWhiteSpace(page.ToString()) || string.IsNullOrWhiteSpace(hash.ToString()))
{
    MessageBox.Show("No Bookmark has been saved !");
}
else
{
    NavigationService.Navigate(new Uri("/myWeb.xaml?Page=" + page + "&id=" + hash, UriKind.Relative));
}

Upvotes: 1

Ajay
Ajay

Reputation: 6590

You have to check IsolatedStorageSettings.ApplicationSettings["qsPage"]; is returning null or any value. try this.

 object pagedata = null,hashdata = null;
if(IsolatedStorageSettings.ApplicationSettings.Contains("qsPage") && IsolatedStorageSettings.ApplicationSettings.Contains("Ayath"))
{
  var page = IsolatedStorageSettings.ApplicationSettings["qsPage"];
  var hash = IsolatedStorageSettings.ApplicationSettings["Ayath"];

  pagedata = page;
  hashdata = hash;
}
 if (pagedata == null && hashdata == null)
// or if i use if (page == null || hash == null)
{    
 MessageBox.Show("No Bookmark has been saved !");
}
else
{
 NavigationService.Navigate(new Uri("/myWeb.xaml?Page=" + pagedata + "&id=" + hashdata, UriKind.Relative));
}

Upvotes: 1

Paul Michaels
Paul Michaels

Reputation: 16705

Try:

if (page == null || hash == null)

Instead. You're query requires both variables to be null.

Upvotes: 1

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