Beginning Perl Programming: From Novice to Professional

© William "Bo" Rothwell of One Course Source, Inc. 2019

William "Bo" RothwellBeginning Perl Programminghttps://doi.org/10.1007/978-1-4842-5055-6_14

14. Debugging Perl

William “Bo” Rothwell¹ 

(1)

San Diego, CA, USA

 

The -w Switch

The -w switch (option) will tell Perl to look for and report unusual code. This code typically includes a logical (not syntax) error and includes (but not excluded to) the following:

• Variable names that are mentioned only once

• Scalar variables that are set before use

• Redefined subroutines

• References to undefined filehandles

• References to filehandles opened read-only that the script is attempting to write to

• Values used as a number that don’t look like numbers

• Arrays used in scalar context

• Subroutines that “recurse” more than 100 deep ...