4 type of Error
i. Parser Error
- Caused by Incorrect syntax/ bad grammar within HTML/ ASP .Net Page
eg.
ii. Compilation Error
- Cause by syntax error, but different with parser error, it is occurs due to the statements are not recognized by language compiler, rather than HTML/ ASP .Net.
* raised when the page in the process being compiled( b4 compile being start )
eg. txtName.value = "super";
cant recognized by compiler, textbox don't have value this probability.
iii. Configuration Error
- Cause by problem in either Web Config/ Machine Config File.
eg.
missing close statement, XML must have < xxx> or
iv. Runtime Error / Logical Error
- Occur during Runtime, after the page is successfully.
- Cant detect by Compiler ( difference between other 3 errors)
What is Exception??
The exception are any error condition or unexpected behavior that occurs during the execution of a program.
It disrupts the normal flow of execution.
Exception Handling Methods
Page-Level Error Handling
try...catch...finally
eg. try
{ your statement }
catch ( Exception e)
{ statements occur when error occur}
finally
{ statements in this block is "FORCED" to be executed irrespective of the fact that an exception has been
raised}
Page_Error()
eg.
protected void Page_Error( object sender, EventArgs e)
{
Exception ex = Server.GetLastError().GetBaseException();
Response.Write(ex.Message.ToString());
Server.ClearError();
}
When page error, The error message will be display by response.write.
you also can redirect to other page by using this method.
Application_Error() Method
In Global.asax, we can find 1 event handler name as Application_Error()
We can write code inside the event.
Different between this 3 methods is :
try...catch...finally - within a block of code
Page_Error() - within a page
Application_Error - within application
Benefits Custom Error Page in an application
users might not understand technical details of exception, so we can provide them a user-friendly error page.
