Skip to main content

ThrowError

ThrowError (Statement)​

Format​

throwerror int_expr
throwerror ( int_expr )

Description​

Cause a runtime error to occur, with the number given. It is handled like any other error: it can be caught with Try / Catch / EndTry or an OnError trap, and without one the program stops. Thrown from inside a Subroutine or Function, it jumps right out of it to the catch.

Use a number that BASIC-256 does not use itself (see Error Codes), for example 1000 or more: LastErrorMessage then returns "User thrown error number". A number that BASIC-256 already uses gets that error's message.

Example​

for speed = 50 to 150 step 50
   try
      call setspeed(speed)
   catch
      print "error " + lasterror + ": " + lasterrormessage
   end try
next speed
end

subroutine setspeed(s)
   if s > 100 then throwerror 1001
   print "speed set to " + s
end subroutine

will display

speed set to 50
speed set to 100
error 1001: User thrown error number

With an OnError trap:

onerror errortrap
print "before error"
throwerror 99
print "after error"
end

errortrap:
print "error " + lasterror + " happened"
return

will display

before error
error 99 happened
after error

See Also​

Error Codes, Lasterror, Lasterrorextra, Lasterrorline, Lasterrormessage, Offerror, Onerror, ThrowError, Try / Catch / EndTry

History​

0.9.6.75New To Version