Exit codes

When a program ends it returns a number to whatever started it. Zero means success to every shell and build tool; anything else is a failure whose number the caller can test. A program that can fail should say so through its exit code, not only through what it prints.

'' The exit code is what a script or a build tool checks.
function CountErrors( ) as int32
    return 4
end function

var errors = CountErrors( )
print errors; " errors found"

'' end n stops the program here with exit status n.
if errors > 0 then end errors

print "not printed: the program has already ended"

Output, and exit code 4:

 4 errors found

end n stops the program at once with exit status n. Reaching the end of the program, or a bare end, exits with 0. The caller reads the code as $? in a Unix shell, %ERRORLEVEL% in cmd.exe, or as the result of exec or shell in another tiko program.

end does not return to the caller of the current procedure; it ends the whole program, so a procedure deep in the program can stop it. Use it for the program's final answer, and let errors inside the program travel by the means in Error Handling.

Activities

1. Change CountErrors to return 0 and check the exit code in your shell.
2. Exit with 1 when the program is given no arguments.