Discover how to use the special system error variable.
- [Voiceover] Perl provides a special variable…that contains the current value…of the operating system's global error condition.…Here is a working copy of errno.pl…from chapter seven of the exercise files.…And you'll notice that there is a "filename",…"notfound.txt",…and in our folder over here we do not have that file.…And I test to see if that file exists…with the "file exists" operator,…and we'll talk more about these operators…later on in this course.…And if it's found, it says "found",…if not, it says "error" and displays the error message…with the dollar exclamation point.…
That's the special variable…that contains the value of that global error number.…And in this case,…because we're using it in a string context,…it'll display the error string.…So when I run this,…it says "error: No such file or directory",…which is the standard error message…for trying to find a file that does not exist.…Now, this special errno value is available…in both numeric and string form.…So, if instead here I say…"my errorstring equals $!"…
Watch to learn the details of the Perl syntax, from variables, conditionals, loops, and data structures to regular expressions, functions, and references. A quick-start guide is included for experienced developers who want to get up and running with Perl 5 fast, and the entire course is recommended for both new and experienced programmers alike. Later chapters cover file handling and reusing code with Perl modules, plus Perl best coding practices.
- Understanding Perl's general syntax and the anatomy of a Perl script
- Writing statements and expressions
- Creating assignments
- Working with variables and strings
- Using data types effectively
- Defining logical flow with conditionals and loops
- Using special variables
- Using Perl operators
- Performing simple Perl programming tasks with expressions
- Matching data
- Defining and calling functions
- Using references
- Handling files in the file I/O
- Using built-in functions
- Reusing code with modules
- Coding with Perl best practices
Skill Level Intermediate
1. Setting Up
About Perl3m 36s
2. Quick Start
3. Basic Syntax
4. Values and Variables
7. Special Variables
9. Regular Expressions
11. References and Structures
12. File I/O
13. Built-In Functions
15. Best Practices
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