Values are showing null on button click

Question

Hi, My Code is: public partial class RoughPage : System.Web.UI.Page { byte [] imageSize; public int a; protected void Page_Load(object sender, EventArgs e) { } public void btnUpload_Click(object sender, EventArgs e) { if (ImgUpload.HasFile) { a = 8 ; imageSize = new byte [ImgUpload.PostedFile.ContentLength]; HttpPostedFile uploadedImage = ImgUpload.PostedFile; uploadedImage.InputStream.Read(imageSize, 0 , ( int )ImgUpload.PostedFile.ContentLength); hfPic.Value = "Y" ; } } public void btnUpload1_Click(object sender, EventArgs e) { int b = a; byte [] aa = imageSize; } } Plz tell me, why value of 'b' and 'aa' are null on "btnUpload1_Click". how to get value of 'imageSize' Thanks in advance

Nilesh Shah · Answer

because those are two separate methods, and both btnUpload_Click and btnUpload1_Click are fired separately (i.e. in different page cycles) Because of the page post back, those values are not persisted. simple solution is to store those values in Session variables but I also suggest you to refactor your code - why size of a file uploaded in one control is needed in another one?

Vincent Maverick Durano · Answer

It's null because when you click the btnUpload1_Click, it will trigger a full postback and your variables a and imagesize won't persist the values that you assigned within your first Button. You can see this by debugging your code by setting a break point in your Button click's event. You should read the basics on how ASP.NET works especially the page life cycle before doing some code like this.

Values are showing null on button click

Answers (2)