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For 2023 - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
How to generate an error message and exit

Posted by admin (Graham Ellis), 9 March 2004
Question - How do I get my Perl program to display an error message and exit?

Answer - use the die function - for example
     die "Unable to open input file";

Question - That's great, but how do I prevent it telling me the line number it failed at in my code?

Answer - add a \n to the end of the string you pass to die - for example
     die "Unable to open input file\n";

Question - What if I'm writing a Perl module that another programmer will be using?   Can I tell him the line number in his code that the failure occurs at?

Answer - use croak instead of die.  You'll need to call in the standarp Perl carp module.  For example
     use carp;
     croak "Unable to open input file";

Edit - it's probably a good idea to tell the user as much useful information as you can in an error message.  My example should really have given the name of the file that wasn't available. Just saying "cannot open file" is unhelpful and prone to lead to lots of support calls

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