Starting from XC=BASIC version 3, certain runtime errors are trappable using the ON ERROR GOTO statement. You can specify a custom error handling routine that makes it possible to recover from errors when needed. The following example demonstrates this functionality:

ON ERROR GOTO errhandler
DIM d$ AS STRING * 6

start:
  INPUT "enter divisor "; d$
  PRINT "10/"; d$; "="; 10.0 / VAL(d$)
  END

errhandler:
  IF ERR() = 20 THEN
    PRINT "division by zero error"
    GOTO start
  END IF

When an error occurs, the ERR() function returns the error code, a number between 0 and 255. The following are built-in errors in XC=BASIC:

Apart from the built-in errors, you can define your own error codes, too. You can use the ERROR command to trigger any error, built-in or custom.

ON ERROR GOTO errhandler
ERROR 99
END
errhandler:
  IF ERR() = 99 THEN PRINT "my custom error occured" ELSE PRINT "other error"