This document covers the following topics:
To explicitly mark the end of a statement, you can place a semicolon (;) between the statement and the next statement. This can be used to make the program structure clearer, but is not required.
statement is used to mark the end of a Natural program, function, subprogram, external subroutine or
Every one of these objects must contain an
statement as the last statement.
Every object may contain only one
statement is used to terminate the execution of a Natural application. A
STOP statement executed anywhere within an application immediately
stops the execution of the entire application.
TERMINATE statement stops the
execution of the Natural application and also ends the Natural session.
During the development of a Natural application and in test
situations, the user should be able to interrupt a running Natural application
that does not respond anymore, for example, due to an endless loop. As the
Natural session should not need to be killed, the running Natural application
can be interrupted via the typical system interrupt key combination (for
example, CTRL+BREAK for Windows, CTRL+C for UNIX and
OpenVMS). The Natural error NAT1016 is raised and the runtime error processing
is activated. The error can be handled by an
ON ERROR processing.
In a production environment, this feature will typically need to be disabled, because the application may not be able to recover from a user interrupt at an arbitrary program location.
The Natural profile parameter
whether interrupts are allowed. By default, interrupts are not allowed.
If this parameter is set to
ON, a running Natural
application may be interrupted with the interrupt key combination of the
operating system (for example, for Windows: CTRL+BREAK; for UNIX:
typically CTRL+C, but can be reconfigured using the
stty command; for OpenVMS: CTRL+C).
Natural catches this interrupt request and then offers the user the following possibilities:
Perform standard error processing by raising a NAT1016 error.
Continue application processing (cancel interrupt).
The choice is shown in a window that is opened after catching the interrupt signal.