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====== Try - Catch ======

The ''Try - Catch'' block is very important, and should be used where an error can occur, for example if a file that needs to be read does not exist, you are specifying an invalid path, the current user has not the rights to read and so forth - please read the documentation about [[https://docs.microsoft.com/en-us/dotnet/api/system.io.file.readalltext|System.IO.File.ReadAllText()]] to see what type of exceptions there are.

In classic VO and Win32 applications, you had to check the return value of an operation, and then eventually ask for more details.

The .NET Framework works differently: it produces an exception, and it is the programmers responsability to treat it correctly.

A sample:<code visualfoxpro>using System.IO

function TestException() as void
local cBuffer as string
	
try
		
cBuffer := File.ReadAllText( "c:\temp\This is an  invalid filename : txt" )
	
catch oEx as ArgumentException
	
System.Console.WriteLine( "invalid argument:" + oEx:Message + " in argument " + oEx:ParamName )
	
catch oEx as NotSupportedException
	
System.Console.WriteLine( "invalid path: " + oEx:Message )

catch oEx as Exception
		
System.Console.WriteLine( "Error reading the file: " + oEx:Message )
	
end try
	
return</code>

If you don't use the ''Try - Catch'' block, your program is terminated with a unspecified error, and you will not be able to understand what really occurred.

Please see also here: [[exceptions|Exceptions]]