Perl Scripting Mastery: Loops, Subroutines, Regex & File Ops

Use the range operator double dot to copy a subarray into a new array; for example, extract elements 2 to 4 from list into my_team, then print the results.

Discover how to count array elements in Perl using the scalar operator and the $hash list, and introduce an input hash with key-value pairs accessed by keys.

The for each loop iterates a list in order using $_; the range operator can create 1 to 9 to sum values, and do while tests at the end.

Explore practical Perl loop controls, including for each, next and last, to filter even and odd elements, accumulate sums, and control flow with continue blocks.

Explore the continue block for selective printing while the body computes sums, then use redo to re-run the loop when sum equals four to add three.

Explore how the Perl redo statement restarts the current loop iteration from the top until the sum reaches ten, then proceeds to subsequent elements.

Learn perl relational operators to test numeric and string conditions; numeric uses ==, !=, <, >, <=, >=, while strings use equal to, not equal to, less than, greater than.

Explore Perl logical operators for numeric and string contexts, including and, or, and not, with examples of concatenation, repetition, range, increment, decrement, and the arrow operator for hashes and objects.

Explore global and local variables in Perl, using the my keyword to define scope, and see how subroutines access and modify scalar and array data.

Open and write to data.txt, then read with the diamond operator and file handles. Compare overwriting versus appending when writing to data two.txt, and explore standard input/output in Perl.

Explore Perl file IO by opening, reading, writing, and appending with file handles, and learn why closing handles matters; compare scalar and array contexts for reading whole files versus lines.

Learn how to test files in Unix using options like -r, -b, -d, -e, -f, -m, -s, -n, -T, -w, and -z to verify readability, existence, type, size, and emptiness.

Explore perl directory and file operations, including open dir, read dir, close dir, mkdir, rmdir, chmod, and chown, then master string functions like length, lc, uc, index, and rindex.

Demonstrate push and pop operations on arrays used as stacks, where the last inserted element is popped first, and reveal how shift and unshift affect the left end of list.

Build a hash from an array using for each, then apply grep on the temp hash to identify common elements with a second array. Use negation to reveal the differences.

Master regex by examining quantifiers, anchors, and alternation in Perl. Explore exact repetitions, optional matches, and escaping to build powerful search patterns.

Master escaping and delimiting in regular expressions, and anchoring with start and end of line. Use groups like ., \s, \d, \w, and Foo|Bar|Baz to match patterns.

Master regex patterns using backslash groups, digit and whitespace matching with \d and \s, dot-star, and square bracket character sets to match precise three-digit sequences.