Handling of error occurring atRun-time is known as Exception handling. Exception handling is a way to preventapplication from crashing.

C# provides three keywords to handleexceptions.

·        try

·        catch

·        finally

The try block

The lines of code which we think cangenerate error; we put them in try block. If exception is raised codecompilation is transferred to catch block.

The catch block

When exception occurs codecompilation is transferred to catch block and code inside catch block isexecuted. We can have more than one catch block for one try block.

The finally block

Finally block is executed after tryblock regardless of the occurrence of error. Finally block contains all cleanupcodes. For example, if there is no need of open connection to the databaseafter try block we can write code for connection close in finally block.

Example

try
           {
               System.Data.SqlClient.SqlCommandBuilder cb;
               cb = new System.Data.SqlClient.SqlCommandBuilder(da);
               DataRow dr = dt.Rows[count];
               dr[0] = txtId.Text;
               dr[1] = txtName.Text;
               dr[2] = txtAddress.Text;
               da.Update(ds, "Employee");
               MessageBox.Show("DataUpdates");
           }

Catch block will catch any erroroccurred in try block and display message

box with exception detail.

           catch (Exceptionex)
           {
               MessageBox.Show(ex.Message);
           }

Finally block will be executedregardless of error occurred or not.

           finally
           {
               con.Close();
           }