catch() - catch an evaluation error

mixed catch( mixed expr );

Evaluate  <expr>.  If  there  is no error, 0 is returned. If there is a
standard error, a string (with a leading '*') will be returned.

The function throw() can also be used to immediately return any  value,
except 0. catch() is not really a function call, but a directive to the
compiler.

The catch() is somewhat costly, and should not be used  just  anywhere.
Rather, use it at places where an error would destroy consistency.

error(3), throw(3), error_handler(4)