Ada Example

EXAMPLE:

(from Dr Chris Lokan's webpage. Full Bibliographic Reference)

Safe I/O

type days is (mon, tue, wed, thu, fri, sat, sun); function get_day return days is local_day : days; -- entered by user good_day : boolean := FALSE: -- loop control begin while not good_day loop begin -- while block PUT ("Enter a day name (first 3 letters) : "); GET (local_day); -- this point only reached if valid entry given good_day := TRUE; exception -- exception handler for while block when DATA_ERROR => PUT ("Must be first 3 letters of a day name"); NEW_LINE; SKIP_LINE; end; -- while block end loop; SKIP_LINE; return local_day; end get_day;

So, we can see this is a very generic way to do this. But what if there are a number of possible things that could have gone wrong? This example shows possible exceptions when attempting to read from a file.

exception

when STATUS_ERROR => PUT_LINE ("The file is already open"); when NAME_ERROR => PUT_LINE ("There is no file with that name"); when USE_ERROR => PUT_LINE ("The file cannot be read"); when others => PUT_LINE ("Unexpected error on opening file");

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The End. This compilation of notes was written by Jared Seaman, 5/6/99.