How does this block work in general? I found a simple code for its application, attached it to a button, but it gives me an error, something is by zero (as I understand it, the type cannot be divided by zero) and I have to reset the program …
var number, zero: Integer; begin // Attempting to divide an integer by zero- to raise the exception try zero := 0; number := 1 div zero; ShowMessage('number / zero = '+IntToStr(number)); except ShowMessage('Unknown error'); end; end;
Answer 1, authority 100%
This is a very useful tool, and also very common. I don’t know how you searched on Google if you didn’t find anything on this topic …
Try -> EXCEPT -> END
controls the behavior of a possible exception that may occur in the “TRY” section. If this occurs, then the execution of the code in the “TRY” section stops and immediately jumps to the beginning of the “EXCEPT” section and the code located there is executed to the end, that is, to “END”. Let’s look at an example of handling the “EZeroDevide” exception (division by zero):
... var a: integer; ... begin try a := 1/0; except on EZeroDivide do showmessage('Divide by zero not allowed!'); // handling a SPECIFIC exception end; end;
There is also another exception handling construct:
TRY -> FINALLY -> END
This block functions a little differently: if an exception occurs in the “TRY” section, the code execution will remain in this section and jump to the “FINALLY” section.
But even if no exceptional situation occurs, then at the end of the code execution in “TRY”, the “FINALLY” section will still be executed. This construction is appropriate to use if at the end of work it is necessary to perform operations for, for example, freeing memory. Example:
... try a := 1/0; finally showmessage('Divide by zero not allowed!'); end; ...
... try a := 1/1; finally showmessage('Divide by zero not allowed!'); end; ...
In both cases, a message will be displayed.
Run your project (exe file) outside Delphi and the block will work. It’s just that the translator catches the error before your block