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190
Errors and Error Processing
The error can then be immediately corrected and the statement reentered. A side-effect of this
entry-time check of the syntax is that the time required for assembly is greatly shortened over
what
it
would be if syntax-checking were deferred until assembly.
Errors encountered during the assembly process are indicated by the assembler in three ways:
• The message -
1. .....
Li···j)·
nn
is displayed. nn is the line number of the IASSEMBLE statement. This is a fatal BASIC
error, unless otherwise trapped.
• Each line in the source code containing an assembly error is printed on the current system
printer. Included is the message -
followed by the error type.
• The message -
follows the listing of the individual errors. The total number of errors is also printed.
An explanation of the individual assembly-time errors can be found at the end of this chapter.
Run-Time Errors
Run-time errors can sometimes be anticipated. They come at two distinct times, and your error
processing is different depending upon which of those times are of concern. The times are
"program development" and "production run".
During program development, errors normally are handled using the debugging techniques
detailed in Chapter 8. Care should be taken in recognizing errors during development. Not all
of them are obvious or indicated by an error message - many simply lock up the machine.
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