# DEBUG

> [HTML Version](debugsystemvariable.htm)

_Rewritten December 2023_

The identifier DEBUG can be either a read-only system variable returning the debug level as set by [SET.LIT](set_lit.htm.md), or a standard variable, depending on the following:

•	If the /X:2 compiler switch is specified, then DEBUG is treated as the system variable, provided it has not been previously mapped as a regular user variable.  

•	If the /DEBUG compiler switch is specified, then DEBUG is always treated as a read-only system variable whose value is 1. This is intended to allow an easy way of compiling a program in "debug mode".

•	If neither /X:2 nor /DEBUG switches specified, then DEBUG is treated as an ordinary variable. If not mapped and /M not specified, it will be auto-mapped like any other unmapped variable.

**Example**

if DEBUG then

? "--DEBUG level set to ";DEBUG

else

? "--DEBUG not set"

endif



If the above program was named SHOWDEBUG and compiled using the /X:2 switch, then...

.SET DEBUG

.RUN SHOWDEBUG

\-DEBUG level set to 1



.SET DEBUG 9

.RUN SHOWDEBUG

\--DEBUG level set to 9 



.SET NODEBUG

.RUN SHOWDEBUG

\--DEBUG not set



If compiled without the /X:2 switch, DEBUG would be treated as an unmapped variable, either initialized to 0, or if /M specified, generating an unmapped variable error.

If compiled with both the /DEBUG and /X:2 switches, then regardless of any prior SET DEBUG statement, the result would be...

    .RUN SHOWDEBUG

    --DEBUG level set to 1



**Comments**

Regardless of the compiler switches, DEBUG acts like a variable and not a symbol, and thus cannot be tested by the ++IFxxx [Conditional Compilation](conditionalcompilation.htm.md) directives.

**See Also**

•	[SET.LIT](set_lit.htm.md)

•	[DEBUG ](debug-statements.htm.md)[Statements](debug-statements.htm.md)

•	[COMPIL.LIT](compil_lit.htm.md)