Perl Programming Language Quiz

The shift function removes and returns the first element of an array. This is functionally equivalent to splice(@array, 0, 1), which removes one element starting at index 0. Distractors represent splicing from the end or inserting sublists.

pop() removes the last element from an array. splice(@array, @array-1, 1) does the same: it starts at the last index (@array-1) and removes 1 element. Option A removes the first element. Options C and D add elements rather than removing.

Perl arrays are 0-indexed. @array = (1,2,3) has indices 0,1,2. Accessing $array[3] is out of bounds. Unlike many languages, Perl returns undef (undefined value) rather than throwing an error. undef prints as empty string, which appears as null/empty. Option D correctly identifies this as null value.

In Perl, the sort function is non-destructive and returns the sorted list without modifying the original array in-place. Because the return value is discarded, @array remains unchanged as 10 30 20. Distractors assume in-place sorting or numerical conversion.

chop() removes the last character from each element of the array when applied to an array. The array (cat, rat, mat) becomes (ca, ra, ma) after chop removes 't' from each element. When printed together, they display as 'caramama' but the expected output format is space-separated as 'ca ra ma'.

In Perl, substr() can be used as an lvalue (left side of assignment). substr($string,6) refers to position 6 onwards in the string. In Hello World, position 6 is 'W', so assigning Perl to that position replaces World with Perl, yielding Hello Perl.

Perl uses lt for string (lexicographic) comparison, not numeric. 143 lt 34 compares character by character: '1' vs '3' - in ASCII, '1' (49) is less than '3' (51), so the condition is true and it prints If is true.

When an array is assigned to a list of scalars in list context, elements are assigned sequentially. $scalar1 gets the first element (1) and $scalar2 gets the second element (2). The print statements output these values.

Evaluating a list literal inside parenthesized syntax in a scalar context triggers the comma operator, which discards all but the last element. Thus, $scalar is assigned 30. Distractors like 10 or 3 assume array size or first-element behavior.

By default, Perl's sort function performs a standard ASCII-betical (lexicographical) comparison. When sorting the strings '100', '80', and '70', '100' comes first because its leading character '1' is ASCII-ordered before '7' and '8', yielding 100 70 80.

In Perl, the -z file test operator specifically returns true if the specified file exists and has a size of zero bytes (meaning it is empty). The -s operator returns the file size, which is used to check if a file is not empty.

The pattern /d[^oO]g/ means: d followed by any character EXCEPT o or O, followed by g. dog fails (has o), dOg fails (has O), doOg fails (first match do has o). dig matches because d is followed by i (not o/O), then g.

The tr/abc/123 operator transliterates: a→1, b→2, c→3. Other characters pass through. 'abdce' becomes '12d3e'. The tr operator returns the number of transliterations made (3), which becomes $output's value. Print outputs both strings.

(?: ...) in regex is a non-capturing group. It groups the subpattern (one or more letters) without storing the matched text in memory (unlike ordinary parentheses which create capture groups). This saves memory when you don't need backreferences.

Perl has predefined special subroutines: BEGIN (runs at compile time), END (runs at program end), AUTOLOAD (handles undefined subroutine calls), DESTROY (for object cleanup), INIT, CHECK. DEFAULT is NOT a predefined Perl subroutine.

The delete function is specifically designed to remove a key-value pair from a hash (associative array). push/pop/shift/unshift are array operations that don't apply to hashes. delete is the correct and idiomatic way to remove hash elements.

The regex o* matches zero or more o's. In GoodWorld, the pattern matches at position 0 with zero o's (the * allows zero matches). The substitution i replaces this zero-length match, inserting i at the beginning. Result: iGoodWorld.

The =~ binding operator with m// returns a boolean: true (1) if match succeeds, false (empty string) if it fails. Here, /(.*)/ matches the entire string successfully, so the expression returns 1 (true), which is assigned to $data and printed.

$hash{'hi'} contains a reference to another hash ({'hello' => 'all'}). When you print a hash reference directly, Perl shows its type and memory address: HASH(0x...) with hex digits. To see the contents, you'd need to dereference.

The ref() function returns the type of a reference (HASH, ARRAY, etc.). For a plain scalar like 'x' (which is not a reference), ref() returns an empty string (false value). It doesn't return 'scalar' - that's a data type, not a reference type.