Perl use VARs pragma skills _ Application Tips

The VARs in Perl is a pragma (precompiled indicator) in Perl that is designed to predefined global variables, which are available in the QW () list and are used throughout the referenced Perl file, even if using use strict do not complain:

 code as follows:

Use strict;
$str = "Hello world!\n";

Error message: Global symbol "$STR" requires explicit package name at ~vars.pl Line 3.
Execution of ~vars.pl aborted due to complication errors.

To perform the result after referencing the use VARs:

 code as follows:

Use strict;
Use VARs QW ($STR);
$str = "Hello world!\n";
Print $str;

Output:

Hello world!