Perl Built-ins Quick Reference

1. String Functions

length

Returns the length of a string.

my $str = "Hello, World!";
my $len = length($str);
print "Length: $len\n";  # Output: Length: 13

substr

Extracts a substring from a string.

my $str = "Hello, World!";
my $sub = substr($str, 0, 5);
print "Substring: $sub\n";  # Output: Substring: Hello

index

Returns the position of a substring within a string.

my $str = "Hello, World!";
my $pos = index($str, "World");
print "Position: $pos\n";  # Output: Position: 7

rindex

Returns the last position of a substring within a string.

my $str = "Hello, World! World!";
my $pos = rindex($str, "World");
print "Last Position: $pos\n";  # Output: Last Position: 14

uc

Converts a string to uppercase.

my $str = "Hello, World!";
my $uc_str = uc($str);
print "Uppercase: $uc_str\n";  # Output: Uppercase: HELLO, WORLD!

lc

Converts a string to lowercase.

my $str = "Hello, World!";
my $lc_str = lc($str);
print "Lowercase: $lc_str\n";  # Output: Lowercase: hello, world!

ucfirst

Converts the first character of a string to uppercase.

my $str = "hello, world!";
my $ucfirst_str = ucfirst($str);
print "Ucfirst: $ucfirst_str\n";  # Output: Ucfirst: Hello, world!

lcfirst

Converts the first character of a string to lowercase.

my $str = "Hello, World!";
my $lcfirst_str = lcfirst($str);
print "Lcfirst: $lcfirst_str\n";  # Output: Lcfirst: hello, World!

chomp

Removes the trailing newline from a string.

my $str = "Hello, World!\n";
chomp($str);
print "Chomped: $str\n";  # Output: Chomped: Hello, World!

chop

Removes the last character from a string.

my $str = "Hello, World!";
chop($str);
print "Chopped: $str\n";  # Output: Chopped: Hello, World

2. Array Functions

push

Adds one or more elements to the end of an array.

my @array = (1, 2, 3);
push @array, 4, 5;
print "Array: @array\n";  # Output: Array: 1 2 3 4 5

pop

Removes and returns the last element of an array.

my @array = (1, 2, 3);
my $last_element = pop @array;
print "Last Element: $last_element\n";  # Output: Last Element: 3

shift

Removes and returns the first element of an array.

my @array = (1, 2, 3);
my $first_element = shift @array;
print "First Element: $first_element\n";  # Output: First Element: 1

unshift

Adds one or more elements to the beginning of an array.

my @array = (2, 3);
unshift @array, 0, 1;
print "Array: @array\n";  # Output: Array: 0 1 2 3

splice

Adds or removes elements from an array.

my @array = (1, 2, 3, 4, 5);
splice @array, 2, 2, (6, 7);
print "Array: @array\n";  # Output: Array: 1 2 6 7 5

sort

Sorts an array.

my @array = (3, 1, 4, 1, 5, 9);
my @sorted_array = sort @array;
print "Sorted Array: @sorted_array\n";  # Output: Sorted Array: 1 1 3 4 5 9

reverse

Reverses an array or string.

my @array = (1, 2, 3);
my @reversed_array = reverse @array;
print "Reversed Array: @reversed_array\n";  # Output: Reversed Array: 3 2 1

join

Joins elements of an array into a string.

my @array = ("Hello", "World");
my $str = join(" ", @array);
print "Joined String: $str\n";  # Output: Joined String: Hello World

split

Splits a string into an array.

my $str = "Hello World";
my @array = split(" ", $str);
print "Array: @array\n";  # Output: Array: Hello World

3. Hash Functions

keys

Returns the keys of a hash.

my %hash = (a => 1, b => 2, c => 3);
my @keys = keys %hash;
print "Keys: @keys\n";  # Output: Keys: a b c

values

Returns the values of a hash.

my %hash = (a => 1, b => 2, c => 3);
my @values = values %hash;
print "Values: @values\n";  # Output: Values: 1 2 3

each

Iterates over key-value pairs in a hash.

my %hash = (a => 1, b => 2, c => 3);
while (my ($key, $value) = each %hash) {
    print "$key => $value\n";
}
# Output:
# a => 1
# b => 2
# c => 3

exists

Checks if a key exists in a hash.

my %hash = (a => 1, b => 2, c => 3);
if (exists $hash{a}) {
    print "Key 'a' exists\n";  # Output: Key 'a' exists
}

delete

Deletes a key-value pair from a hash.

my %hash = (a => 1, b => 2, c => 3);
delete $hash{b};
print "Hash after deletion: ", %hash, "\n";  # Output: Hash after deletion: a1c3

4. File Handling Functions

open

Opens a file.

open(my $fh, '<', 'file.txt') or die "Could not open file: $!";

close

Closes a file.

close($fh);

read

Reads from a file.

my $buffer;
read($fh, $buffer, 1024);

write

Writes to a file.

print $fh "Hello, World!\n";

seek

Moves the file pointer.

seek($fh, 0, 0);  # Move to the beginning of the file

tell

Returns the current position of the file pointer.

my $pos = tell($fh);
print "Current Position: $pos\n";

eof

Checks if the end of the file has been reached.

if (eof($fh)) {
    print "End of file reached\n";
}

5. Regular Expression Functions

m//

Matches a regular expression.

my $str = "Hello, World!";
if ($str =~ m/World/) {
    print "Match found\n";  # Output: Match found
}

s///

Substitutes a regular expression.

my $str = "Hello, World!";
$str =~ s/World/Perl/;
print "Substituted String: $str\n";  # Output: Substituted String: Hello, Perl!

tr///

Translates characters.

my $str = "Hello, World!";
$str =~ tr/a-z/A-Z/;
print "Translated String: $str\n";  # Output: Translated String: HELLO, WORLD!

6. Mathematical Functions

abs

Returns the absolute value.

my $num = -42;
my $abs_num = abs($num);
print "Absolute Value: $abs_num\n";  # Output: Absolute Value: 42

sqrt

Returns the square root.

my $num = 16;
my $sqrt_num = sqrt($num);
print "Square Root: $sqrt_num\n";  # Output: Square Root: 4

int

Returns the integer part of a number.

my $num = 3.14;
my $int_num = int($num);
print "Integer Part: $int_num\n";  # Output: Integer Part: 3

rand

Returns a random number.

my $rand_num = rand(10);
print "Random Number: $rand_num\n";  # Output: Random Number: [0, 10)

srand

Seeds the random number generator.

srand(42);
my $rand_num = rand(10);
print "Seeded Random Number: $rand_num\n";

7. Time Functions

time

Returns the current time in seconds since the epoch.

my $current_time = time;
print "Current Time: $current_time\n";

localtime

Converts a time to local time.

my @local_time = localtime(time);
print "Local Time: @local_time\n";

gmtime

Converts a time to GMT.

my @gm_time = gmtime(time);
print "GMT: @gm_time\n";

sleep

Pauses the script for a specified number of seconds.

sleep(5);
print "Slept for 5 seconds\n";

8. Miscellaneous Functions

defined

Checks if a variable is defined.

my $var;
if (defined $var) {
    print "Variable is defined\n";
} else {
    print "Variable is not defined\n";  # Output: Variable is not defined
}

undef

Undefines a variable.

my $var = 42;
undef $var;
if (defined $var) {
    print "Variable is defined\n";
} else {
    print "Variable is not defined\n";  # Output: Variable is not defined
}

ref

Returns the reference type of a variable.

my $array_ref = [1, 2, 3];
my $ref_type = ref($array_ref);
print "Reference Type: $ref_type\n";  # Output: Reference Type: ARRAY

eval

Evaluates a string as Perl code.

my $code = 'print "Hello, World!\n"';
eval $code;  # Output: Hello, World!

die

Exits the script with an error message.

die "Fatal error occurred\n";

warn

Prints a warning message.

warn "This is a warning\n";

exit

Exits the script.

exit;

---

9. List and Scalar Functions

grep

Filters elements of a list based on a condition.

my @numbers = (1, 2, 3, 4, 5);
my @even_numbers = grep { $_ % 2 == 0 } @numbers;
print "Even Numbers: @even_numbers\n";  # Output: Even Numbers: 2 4

map

Transforms elements of a list.

my @numbers = (1, 2, 3);
my @squared_numbers = map { $_ * $_ } @numbers;
print "Squared Numbers: @squared_numbers\n";  # Output: Squared Numbers: 1 4 9

scalar

Returns the number of elements in an array in scalar context.

my @array = (1, 2, 3);
my $count = scalar @array;
print "Array Count: $count\n";  # Output: Array Count: 3

reverse (in scalar context)

Reverses a string.

my $str = "Hello, World!";
my $reversed_str = scalar reverse $str;
print "Reversed String: $reversed_str\n";  # Output: Reversed String: !dlroW ,olleH

---

10. Input/Output Functions

print

Prints output to standard output.

print "Hello, World!\n";  # Output: Hello, World!

printf

Formats and prints output.

my $name = "Alice";
my $age = 30;
printf "Name: %s, Age: %d\n", $name, $age;  # Output: Name: Alice, Age: 30

say

Prints output with a newline (requires use feature 'say';).

use feature 'say';
say "Hello, World!";  # Output: Hello, World! (with newline)

readline

Reads a line from a filehandle.

open(my $fh, '<', 'file.txt') or die "Cannot open file: $!";
my $line = readline($fh);
print "First Line: $line\n";
close($fh);

getc

Reads a single character from a filehandle.

open(my $fh, '<', 'file.txt') or die "Cannot open file: $!";
my $char = getc($fh);
print "First Character: $char\n";
close($fh);

---

11. File Test Operators

-e

Checks if a file exists.

if (-e 'file.txt') {
    print "File exists\n";
} else {
    print "File does not exist\n";
}

-f

Checks if a file is a plain file.

if (-f 'file.txt') {
    print "It's a plain file\n";
}

-d

Checks if a file is a directory.

if (-d 'directory') {
    print "It's a directory\n";
}

-r

Checks if a file is readable.

if (-r 'file.txt') {
    print "File is readable\n";
}

-w

Checks if a file is writable.

if (-w 'file.txt') {
    print "File is writable\n";
}

-x

Checks if a file is executable.

if (-x 'script.pl') {
    print "File is executable\n";
}

-s

Returns the size of a file in bytes.

my $size = -s 'file.txt';
print "File Size: $size bytes\n";

---

12. System Interaction Functions

system

Executes a system command.

system("ls -l");  # Lists files in the current directory

exec

Replaces the current process with another program.

exec("ls -l");  # Replaces the Perl script with the `ls` command

backticks (``)

Captures the output of a system command.

my $output = `ls -l`;
print "Command Output:\n$output\n";

fork

Creates a child process.

my $pid = fork;
if ($pid == 0) {
    print "Child Process\n";
    exit;
} else {
    print "Parent Process\n";
}

wait

Waits for a child process to finish.

my $pid = fork;
if ($pid == 0) {
    print "Child Process\n";
    exit;
} else {
    wait;
    print "Parent Process: Child finished\n";
}

---

13. Error Handling Functions

warn

Prints a warning message to STDERR.

warn "This is a warning message\n";

die

Exits the program with an error message.

die "Fatal error occurred\n";

eval

Evaluates a block of code and catches errors.

eval {
    die "An error occurred\n";
};
if ($@) {
    print "Error caught: $@\n";
}

---

14. Reference and Data Structure Functions

ref

Returns the type of a reference.

my $array_ref = [1, 2, 3];
print "Reference Type: ", ref($array_ref), "\n";  # Output: Reference Type: ARRAY

bless

Associates an object with a class.

package MyClass;
sub new {
    my $self = {};
    bless $self, 'MyClass';
    return $self;
}
my $obj = MyClass->new();
print "Object is blessed into: ", ref($obj), "\n";  # Output: Object is blessed into: MyClass

defined

Checks if a variable is defined.

my $var;
if (defined $var) {
    print "Variable is defined\n";
} else {
    print "Variable is not defined\n";  # Output: Variable is not defined
}

---

15. Miscellaneous Functions

caller

Returns information about the caller of a subroutine.

sub foo {
    my ($package, $filename, $line) = caller;
    print "Called from package: $package, file: $filename, line: $line\n";
}
foo();

require

Loads a Perl module or file.

require 'module.pl';

use

Loads a Perl module at compile time.

use strict;
use warnings;

package

Declares a package namespace.

package MyPackage;
sub hello {
    print "Hello from MyPackage\n";
}
MyPackage::hello();  # Output: Hello from MyPackage

tie

Binds a variable to a class implementing TIEHASH, TIEARRAY, etc.

tie my %hash, 'Tie::Hash';

---

16. Special Variables and Functions

$_

Default variable for many functions.

foreach (1..5) {
    print "$_\n";  # Output: 1 2 3 4 5
}

@_

Subroutine argument list.

sub greet {
    my ($name) = @_;
    print "Hello, $name!\n";
}
greet("Alice");  # Output: Hello, Alice!

$!

Error message from the last system call.

open(my $fh, '<', 'nonexistent.txt') or die "Error: $!\n";

$@

Error message from the last eval block.

eval { die "An error occurred\n" };
print "Error: $@" if $@;

---

17. Advanced String Functions

quotemeta

Escapes all non-alphanumeric characters in a string.

my $str = "Hello, World! (123)";
my $escaped_str = quotemeta($str);
print "Escaped String: $escaped_str\n";  # Output: Escaped String: Hello\,\ World\!\ \(123\)

pack

Converts a list of values into a binary string.

my $binary_str = pack("C*", 65, 66, 67);
print "Binary String: $binary_str\n";  # Output: Binary String: ABC

unpack

Converts a binary string into a list of values.

my @values = unpack("C*", "ABC");
print "Values: @values\n";  # Output: Values: 65 66 67

chr

Returns the character corresponding to an ASCII value.

my $char = chr(65);
print "Character: $char\n";  # Output: Character: A

ord

Returns the ASCII value of a character.

my $ascii = ord('A');
print "ASCII Value: $ascii\n";  # Output: ASCII Value: 65

---

18. Advanced Array Functions

splice (Advanced Usage)

Replaces elements in an array.

my @array = (1, 2, 3, 4, 5);
splice @array, 1, 2, (6, 7, 8);
print "Array: @array\n";  # Output: Array: 1 6 7 8 4 5

grep (Advanced Usage)

Filters elements based on a complex condition.

my @numbers = (1, 2, 3, 4, 5);
my @filtered = grep { $_ > 2 && $_ < 5 } @numbers;
print "Filtered Numbers: @filtered\n";  # Output: Filtered Numbers: 3 4

map (Advanced Usage)

Transforms elements based on a complex condition.

my @numbers = (1, 2, 3);
my @transformed = map { $_ * 2 } @numbers;
print "Transformed Numbers: @transformed\n";  # Output: Transformed Numbers: 2 4 6

---

19. Advanced Hash Functions

each (Advanced Usage)

Iterates over key-value pairs in a hash.

my %hash = (a => 1, b => 2, c => 3);
while (my ($key, $value) = each %hash) {
    print "$key => $value\n";
}
# Output:
# a => 1
# b => 2
# c => 3

keys (Advanced Usage)

Sorts keys of a hash.

my %hash = (b => 2, a => 1, c => 3);
my @sorted_keys = sort keys %hash;
print "Sorted Keys: @sorted_keys\n";  # Output: Sorted Keys: a b c

values (Advanced Usage)

Sorts values of a hash.

my %hash = (a => 3, b => 1, c => 2);
my @sorted_values = sort values %hash;
print "Sorted Values: @sorted_values\n";  # Output: Sorted Values: 1 2 3

---

20. Advanced File Handling Functions

stat

Returns file statistics.

my @stats = stat('file.txt');
print "File Size: $stats[7] bytes\n";

lstat

Returns file statistics for symbolic links.

my @stats = lstat('symlink.txt');
print "File Size: $stats[7] bytes\n";

rename

Renames a file.

rename('old.txt', 'new.txt') or die "Cannot rename file: $!";

unlink

Deletes a file.

unlink('file.txt') or die "Cannot delete file: $!";

link

Creates a hard link.

link('file.txt', 'hardlink.txt') or die "Cannot create hard link: $!";

symlink

Creates a symbolic link.

symlink('file.txt', 'symlink.txt') or die "Cannot create symlink: $!";

mkdir

Creates a directory.

mkdir('new_directory') or die "Cannot create directory: $!";

rmdir

Removes a directory.

rmdir('empty_directory') or die "Cannot remove directory: $!";

---

21. Advanced System Interaction Functions

alarm

Sets a timer to deliver a signal.

alarm(5);
print "Alarm set for 5 seconds\n";

kill

Sends a signal to a process.

kill('TERM', $pid);

getpgrp

Returns the process group ID.

my $pgrp = getpgrp();
print "Process Group ID: $pgrp\n";

setpgrp

Sets the process group ID.

setpgrp(0, 0);

getppid

Returns the parent process ID.

my $ppid = getppid();
print "Parent Process ID: $ppid\n";

getpriority

Returns the current priority of a process.

my $priority = getpriority(0, 0);
print "Process Priority: $priority\n";

setpriority

Sets the priority of a process.

setpriority(0, 0, 10);

---

22. Advanced Error Handling Functions

croak

Exits with an error message (from Carp module).

use Carp;
croak "Fatal error occurred\n";

confess

Exits with a stack trace (from Carp module).

use Carp;
confess "Fatal error occurred\n";

---

23. Advanced Regular Expression Functions

qr

Compiles a regular expression.

my $regex = qr/foo/;
if ("foo" =~ $regex) {
    print "Match found\n";  # Output: Match found
}

pos

Returns or sets the position of the last match.

my $str = "foo bar foo";
$str =~ /foo/g;
print "Position: ", pos($str), "\n";  # Output: Position: 3

study

Optimizes a string for repeated pattern matching.

my $str = "Hello, World!";
study($str);
if ($str =~ /World/) {
    print "Match found\n";  # Output: Match found
}

---

24. Advanced Mathematical Functions

atan2

Returns the arctangent of Y/X in radians.

my $angle = atan2(1, 1);
print "Angle: $angle radians\n";  # Output: Angle: 0.785398163397448 radians

exp

Returns the exponential of a number.

my $exp = exp(1);
print "Exponential: $exp\n";  # Output: Exponential: 2.71828182845905

log

Returns the natural logarithm of a number.

my $log = log(10);
print "Natural Logarithm: $log\n";  # Output: Natural Logarithm: 2.30258509299405

sin

Returns the sine of a number.

my $sin = sin(1);
print "Sine: $sin\n";  # Output: Sine: 0.841470984807897

cos

Returns the cosine of a number.

my $cos = cos(1);
print "Cosine: $cos\n";  # Output: Cosine: 0.54030230586814

rand (Advanced Usage)

Generates a random number within a range.

my $rand_num = int(rand(100));
print "Random Number: $rand_num\n";  # Output: Random Number: [0, 99]

---

25. Advanced Miscellaneous Functions

tied

Returns the object underlying a tied variable.

tie my %hash, 'Tie::Hash';
my $obj = tied %hash;
print "Tied Object: $obj\n";

untie

Breaks the binding between a variable and a package.

untie %hash;

formline

Formats a string (used with format).

formline("Hello, @<<<<", "World");
print $^A;  # Output: Hello, World

vec

Treats a string as a vector of unsigned integers.

my $str = "ABC";
vec($str, 0, 8) = 88;
print "Modified String: $str\n";  # Output: Modified String: XBC

26. Advanced Input/Output Functions

select

Changes the default filehandle for output.

open(my $fh, '>', 'output.txt') or die "Cannot open file: $!";
select $fh;
print "This goes to output.txt\n";
select STDOUT;  # Switch back to STDOUT
print "This goes to the screen\n";
close($fh);

sysread

Reads a fixed number of bytes from a filehandle.

open(my $fh, '<', 'file.txt') or die "Cannot open file: $!";
my $buffer;
sysread($fh, $buffer, 1024);
print "Read Data: $buffer\n";
close($fh);

syswrite

Writes a fixed number of bytes to a filehandle.

open(my $fh, '>', 'output.txt') or die "Cannot open file: $!";
syswrite($fh, "Hello, World!", 13);
close($fh);

fcntl

Performs low-level file control operations.

use Fcntl;
fcntl($fh, F_SETFL, O_NONBLOCK);

ioctl

Performs device-specific input/output operations.

use IO::Handle;
ioctl($fh, 0x1234, $arg);

---

27. Advanced System Interaction Functions

pipe

Creates a pair of filehandles for interprocess communication.

pipe(my $reader, my $writer);
print $writer "Hello, World!\n";
close($writer);
my $message = <$reader>;
print "Message: $message\n";  # Output: Message: Hello, World!
close($reader);

socket

Creates a socket for network communication.

use Socket;
socket(my $sock, PF_INET, SOCK_STREAM, getprotobyname('tcp'));

bind

Binds a socket to an address.

my $port = 12345;
my $addr = sockaddr_in($port, INADDR_ANY);
bind($sock, $addr) or die "Cannot bind socket: $!";

listen

Listens for incoming connections on a socket.

listen($sock, 5) or die "Cannot listen on socket: $!";

accept

Accepts an incoming connection on a socket.

my $client_addr = accept(my $client_sock, $sock);
print "Connection accepted\n";

shutdown

Shuts down a socket.

shutdown($sock, 2);  # 2 means shut down both reading and writing

---

28. Advanced Error Handling Functions

carp

Prints a warning message with a stack trace (from Carp module).

use Carp;
carp "This is a warning message\n";

cluck

Prints a warning message with a full stack trace (from Carp module).

use Carp;
cluck "This is a warning message\n";

eval (Advanced Usage)

Evaluates a block of code and catches errors.

eval {
    die "An error occurred\n";
};
if ($@) {
    print "Error caught: $@\n";
}

---

29. Advanced Regular Expression Functions

qr (Advanced Usage)

Compiles a regular expression with modifiers.

my $regex = qr/foo/i;  # Case-insensitive match
if ("FOO" =~ $regex) {
    print "Match found\n";  # Output: Match found
}

pos (Advanced Usage)

Sets the position of the last match.

my $str = "foo bar foo";
$str =~ /foo/g;
pos($str) = 4;
if ($str =~ /foo/g) {
    print "Match found at position ", pos($str), "\n";  # Output: Match found at position 8
}

study (Advanced Usage)

Optimizes a string for repeated pattern matching.

my $str = "Hello, World!";
study($str);
if ($str =~ /World/) {
    print "Match found\n";  # Output: Match found
}

---

30. Advanced Mathematical Functions

atan2 (Advanced Usage)

Returns the arctangent of Y/X in radians.

my $angle = atan2(1, 1);
print "Angle: $angle radians\n";  # Output: Angle: 0.785398163397448 radians

exp (Advanced Usage)

Returns the exponential of a number.

my $exp = exp(1);
print "Exponential: $exp\n";  # Output: Exponential: 2.71828182845905

log (Advanced Usage)

Returns the natural logarithm of a number.

my $log = log(10);
print "Natural Logarithm: $log\n";  # Output: Natural Logarithm: 2.30258509299405

sin (Advanced Usage)

Returns the sine of a number.

my $sin = sin(1);
print "Sine: $sin\n";  # Output: Sine: 0.841470984807897

cos (Advanced Usage)

Returns the cosine of a number.

my $cos = cos(1);
print "Cosine: $cos\n";  # Output: Cosine: 0.54030230586814

rand (Advanced Usage)

Generates a random number within a range.

my $rand_num = int(rand(100));
print "Random Number: $rand_num\n";  # Output: Random Number: [0, 99]

---

31. Advanced Miscellaneous Functions

tied (Advanced Usage)

Returns the object underlying a tied variable.

tie my %hash, 'Tie::Hash';
my $obj = tied %hash;
print "Tied Object: $obj\n";

untie (Advanced Usage)

Breaks the binding between a variable and a package.

untie %hash;

formline (Advanced Usage)

Formats a string (used with format).

formline("Hello, @<<<<", "World");
print $^A;  # Output: Hello, World

vec (Advanced Usage)

Treats a string as a vector of unsigned integers.

my $str = "ABC";
vec($str, 0, 8) = 88;
print "Modified String: $str\n";  # Output: Modified String: XBC

---

32. Advanced Special Variables

$^O

Returns the operating system name.

print "Operating System: $^O\n";  # Output: Operating System: linux (or darwin, MSWin32, etc.)

$^T

Returns the time the script started running.

print "Script Start Time: $^T\n";  # Output: Script Start Time: [epoch time]

$^X

Returns the name of the Perl executable.

print "Perl Executable: $^X\n";  # Output: Perl Executable: /usr/bin/perl

$^V

Returns the Perl version.

print "Perl Version: $^V\n";  # Output: Perl Version: v5.34.0 (or similar)

$^W

Returns the current value of the warning flag.

print "Warning Flag: $^W\n";  # Output: Warning Flag: 1 (if warnings are enabled)

---

33. Advanced File Test Operators

-M

Returns the age of the file in days since the script started.

my $age = -M 'file.txt';
print "File Age: $age days\n";

-C

Returns the inode change age of the file in days.

my $inode_age = -C 'file.txt';
print "Inode Change Age: $inode_age days\n";

-A

Returns the access age of the file in days.

my $access_age = -A 'file.txt';
print "Access Age: $access_age days\n";

---

34. Advanced Input/Output Functions

sysseek

Moves the file pointer to a specific position.

open(my $fh, '+<', 'file.txt') or die "Cannot open file: $!";
sysseek($fh, 10, 0);  # Move to the 10th byte
print $fh "Hello";
close($fh);

truncate

Truncates a file to a specified length.

open(my $fh, '+<', 'file.txt') or die "Cannot open file: $!";
truncate($fh, 100);  # Truncate file to 100 bytes
close($fh);

flock

Locks a file for exclusive access.

open(my $fh, '>>', 'file.txt') or die "Cannot open file: $!";
flock($fh, 2) or die "Cannot lock file: $!";  # 2 means exclusive lock
print $fh "Exclusive access\n";
flock($fh, 8);  # 8 means unlock
close($fh);

fcntl (Advanced Usage)

Performs low-level file control operations.

use Fcntl;
fcntl($fh, F_SETFL, O_NONBLOCK);

ioctl (Advanced Usage)

Performs device-specific input/output operations.

use IO::Handle;
ioctl($fh, 0x1234, $arg);

---

35. Advanced System Interaction Functions

pipe (Advanced Usage)

Creates a pair of filehandles for interprocess communication.

pipe(my $reader, my $writer);
print $writer "Hello, World!\n";
close($writer);
my $message = <$reader>;
print "Message: $message\n";  # Output: Message: Hello, World!
close($reader);

socket (Advanced Usage)

Creates a socket for network communication.

use Socket;
socket(my $sock, PF_INET, SOCK_STREAM, getprotobyname('tcp'));

bind (Advanced Usage)

Binds a socket to an address.

my $port = 12345;
my $addr = sockaddr_in($port, INADDR_ANY);
bind($sock, $addr) or die "Cannot bind socket: $!";

listen (Advanced Usage)

Listens for incoming connections on a socket.

listen($sock, 5) or die "Cannot listen on socket: $!";

accept (Advanced Usage)

Accepts an incoming connection on a socket.

my $client_addr = accept(my $client_sock, $sock);
print "Connection accepted\n";

shutdown (Advanced Usage)

Shuts down a socket.

shutdown($sock, 2);  # 2 means shut down both reading and writing

---

36. Advanced Error Handling Functions

carp (Advanced Usage)

Prints a warning message with a stack trace (from Carp module).

use Carp;
carp "This is a warning message\n";

cluck (Advanced Usage)

Prints a warning message with a full stack trace (from Carp module).

use Carp;
cluck "This is a warning message\n";

eval (Advanced Usage)

Evaluates a block of code and catches errors.

eval {
    die "An error occurred\n";
};
if ($@) {
    print "Error caught: $@\n";
}

---

37. Advanced Regular Expression Functions

qr (Advanced Usage)

Compiles a regular expression with modifiers.

my $regex = qr/foo/i;  # Case-insensitive match
if ("FOO" =~ $regex) {
    print "Match found\n";  # Output: Match found
}

pos (Advanced Usage)

Sets the position of the last match.

my $str = "foo bar foo";
$str =~ /foo/g;
pos($str) = 4;
if ($str =~ /foo/g) {
    print "Match found at position ", pos($str), "\n";  # Output: Match found at position 8
}

study (Advanced Usage)

Optimizes a string for repeated pattern matching.

my $str = "Hello, World!";
study($str);
if ($str =~ /World/) {
    print "Match found\n";  # Output: Match found
}

---

38. Advanced Mathematical Functions

atan2 (Advanced Usage)

Returns the arctangent of Y/X in radians.

my $angle = atan2(1, 1);
print "Angle: $angle radians\n";  # Output: Angle: 0.785398163397448 radians

exp (Advanced Usage)

Returns the exponential of a number.

my $exp = exp(1);
print "Exponential: $exp\n";  # Output: Exponential: 2.71828182845905

log (Advanced Usage)

Returns the natural logarithm of a number.

my $log = log(10);
print "Natural Logarithm: $log\n";  # Output: Natural Logarithm: 2.30258509299405

sin (Advanced Usage)

Returns the sine of a number.

my $sin = sin(1);
print "Sine: $sin\n";  # Output: Sine: 0.841470984807897

cos (Advanced Usage)

Returns the cosine of a number.

my $cos = cos(1);
print "Cosine: $cos\n";  # Output: Cosine: 0.54030230586814

rand (Advanced Usage)

Generates a random number within a range.

my $rand_num = int(rand(100));
print "Random Number: $rand_num\n";  # Output: Random Number: [0, 99]

---

39. Advanced Miscellaneous Functions

tied (Advanced Usage)

Returns the object underlying a tied variable.

tie my %hash, 'Tie::Hash';
my $obj = tied %hash;
print "Tied Object: $obj\n";

untie (Advanced Usage)

Breaks the binding between a variable and a package.

untie %hash;

formline (Advanced Usage)

Formats a string (used with format).

formline("Hello, @<<<<", "World");
print $^A;  # Output: Hello, World

vec (Advanced Usage)

Treats a string as a vector of unsigned integers.

my $str = "ABC";
vec($str, 0, 8) = 88;
print "Modified String: $str\n";  # Output: Modified String: XBC

---

40. Advanced Special Variables

$^O

Returns the operating system name.

print "Operating System: $^O\n";  # Output: Operating System: linux (or darwin, MSWin32, etc.)

$^T

Returns the time the script started running.

print "Script Start Time: $^T\n";  # Output: Script Start Time: [epoch time]

$^X

Returns the name of the Perl executable.

print "Perl Executable: $^X\n";  # Output: Perl Executable: /usr/bin/perl

$^V

Returns the Perl version.

print "Perl Version: $^V\n";  # Output: Perl Version: v5.34.0 (or similar)

$^W

Returns the current value of the warning flag.

print "Warning Flag: $^W\n";  # Output: Warning Flag: 1 (if warnings are enabled)

---

41. Advanced File Test Operators

-M

Returns the age of the file in days since the script started.

my $age = -M 'file.txt';
print "File Age: $age days\n";

-C

Returns the inode change age of the file in days.

my $inode_age = -C 'file.txt';
print "Inode Change Age: $inode_age days\n";

-A

Returns the access age of the file in days.

my $access_age = -A 'file.txt';
print "Access Age: $access_age days\n";

42. Advanced File and Directory Functions

opendir

Opens a directory for reading.

opendir(my $dh, 'directory') or die "Cannot open directory: $!";
while (my $file = readdir($dh)) {
    print "File: $file\n";
}
closedir($dh);

readdir

Reads entries from a directory handle.

opendir(my $dh, 'directory') or die "Cannot open directory: $!";
my @files = readdir($dh);
closedir($dh);
print "Files: @files\n";

rewinddir

Resets the position of a directory handle to the beginning.

opendir(my $dh, 'directory') or die "Cannot open directory: $!";
readdir($dh);  # Read some entries
rewinddir($dh);  # Reset to the beginning
closedir($dh);

telldir

Returns the current position of a directory handle.

opendir(my $dh, 'directory') or die "Cannot open directory: $!";
readdir($dh);
my $pos = telldir($dh);
print "Directory Position: $pos\n";
closedir($dh);

seekdir

Sets the position of a directory handle.

opendir(my $dh, 'directory') or die "Cannot open directory: $!";
seekdir($dh, 0);  # Reset to the beginning
closedir($dh);

mkdir (Advanced Usage)

Creates a directory with specific permissions.

mkdir('new_directory', 0755) or die "Cannot create directory: $!";

rmdir (Advanced Usage)

Removes an empty directory.

rmdir('empty_directory') or die "Cannot remove directory: $!";

---

43. Advanced Process Control Functions

waitpid

Waits for a specific child process to finish.

my $pid = fork;
if ($pid == 0) {
    print "Child Process\n";
    exit;
} else {
    waitpid($pid, 0);
    print "Parent Process: Child finished\n";
}

getpwnam

Gets user information by name.

my $user_info = getpwnam('root');
print "User Info: $user_info\n";

getgrnam

Gets group information by name.

my $group_info = getgrnam('wheel');
print "Group Info: $group_info\n";

getpwuid

Gets user information by UID.

my $user_info = getpwuid(0);
print "User Info: $user_info\n";

getgrgid

Gets group information by GID.

my $group_info = getgrgid(0);
print "Group Info: $group_info\n";

---

44. Advanced Signal Handling Functions

%SIG

Handles signals in Perl.

$SIG{INT} = sub { print "Caught SIGINT\n"; exit; };
print "Press Ctrl+C to trigger SIGINT\n";
sleep(10);

kill (Advanced Usage)

Sends a signal to a process.

kill('TERM', $pid);

alarm (Advanced Usage)

Sets a timer to deliver a signal.

alarm

45. Advanced Networking Functions

gethostbyname

Gets host information by name.

my $host_info = gethostbyname('localhost');
print "Host Info: $host_info\n";

gethostbyaddr

Gets host information by address.

my $addr = inet_aton('127.0.0.1');
my $host_info = gethostbyaddr($addr, AF_INET);
print "Host Info: $host_info\n";

getservbyname

Gets service information by name.

my $service_info = getservbyname('http', 'tcp');
print "Service Info: $service_info\n";

getservbyport

Gets service information by port.

my $service_info = getservbyport(80, 'tcp');
print "Service Info: $service_info\n";

---

46. Advanced Data Manipulation Functions

pack (Advanced Usage)

Converts a list of values into a binary string.

my $binary_str = pack("C*", 65, 66, 67);
print "Binary String: $binary_str\n";  # Output: Binary String: ABC

unpack (Advanced Usage)

Converts a binary string into a list of values.

my @values = unpack("C*", "ABC");
print "Values: @values\n";  # Output: Values: 65 66 67

vec (Advanced Usage)

Treats a string as a vector of unsigned integers.

my $str = "ABC";
vec($str, 0, 8) = 88;
print "Modified String: $str\n";  # Output: Modified String: XBC

---

47. Advanced Object-Oriented Programming Functions

bless (Advanced Usage)

Associates an object with a class.

package MyClass;
sub new {
    my $self = {};
    bless $self, 'MyClass';
    return $self;
}
my $obj = MyClass->new();
print "Object is blessed into: ", ref($obj), "\n";  # Output: Object is blessed into: MyClass

ref (Advanced Usage)

Returns the type of a reference.

my $array_ref = [1, 2, 3];
print "Reference Type: ", ref($array_ref), "\n";  # Output: Reference Type: ARRAY

tie (Advanced Usage)

Binds a variable to a class implementing TIEHASH, TIEARRAY, etc.

tie my %hash, 'Tie::Hash';

untie (Advanced Usage)

Breaks the binding between a variable and a package.

untie %hash;

---

48. Advanced Miscellaneous Functions

caller (Advanced Usage)

Returns information about the caller of a subroutine.

sub foo {
    my ($package, $filename, $line) = caller;
    print "Called from package: $package, file: $filename, line: $line\n";
}
foo();

require (Advanced Usage)

Loads a Perl module or file.

require 'module.pl';

use (Advanced Usage)

Loads a Perl module at compile time.

use strict;
use warnings;

package (Advanced Usage)

Declares a package namespace.

package MyPackage;
sub hello {
    print "Hello from MyPackage\n";
}
MyPackage::hello();  # Output: Hello from MyPackage

---

49. Advanced Special Variables

$^O

Returns the operating system name.

print "Operating System: $^O\n";  # Output: Operating System: linux (or darwin, MSWin32, etc.)

$^T

Returns the time the script started running.

print "Script Start Time: $^T\n";  # Output: Script Start Time: [epoch time]

$^X

Returns the name of the Perl executable.

print "Perl Executable: $^X\n";  # Output: Perl Executable: /usr/bin/perl

$^V

Returns the Perl version.

print "Perl Version: $^V\n";  # Output: Perl Version: v5.34.0 (or similar)

$^W

Returns the current value of the warning flag.

print "Warning Flag: $^W\n";  # Output: Warning Flag: 1 (if warnings are enabled)

---

50. Advanced File Test Operators

-M

Returns the age of the file in days since the script started.

my $age = -M 'file.txt';
print "File Age: $age days\n";

-C

Returns the inode change age of the file in days.

my $inode_age = -C 'file.txt';
print "Inode Change Age: $inode_age days\n";

-A

Returns the access age of the file in days.

my $access_age = -A 'file.txt';
print "Access Age: $access_age days\n";

---

51. Advanced Input/Output Functions

sysread

Reads a fixed number of bytes from a filehandle.

open(my $fh, '<', 'file.txt') or die "Cannot open file: $!";
my $buffer;
sysread($fh, $buffer, 1024);
print "Read Data: $buffer\n";
close($fh);

syswrite

Writes a fixed number of bytes to a filehandle.

open(my $fh, '>', 'output.txt') or die "Cannot open file: $!";
syswrite($fh, "Hello, World!", 13);
close($fh);

fcntl

Performs low-level file control operations.

use Fcntl;
fcntl($fh, F_SETFL, O_NONBLOCK);

ioctl

Performs device-specific input/output operations.

use IO::Handle;
ioctl($fh, 0x1234, $arg);

---

52. Advanced System Interaction Functions

pipe

Creates a pair of filehandles for interprocess communication.

pipe(my $reader, my $writer);
print $writer "Hello, World!\n";
close($writer);
my $message = <$reader>;
print "Message: $message\n";  # Output: Message: Hello, World!
close($reader);

socket

Creates a socket for network communication.

use Socket;
socket(my $sock, PF_INET, SOCK_STREAM, getprotobyname('tcp'));

bind

Binds a socket to an address.

my $port = 12345;
my $addr = sockaddr_in($port, INADDR_ANY);
bind($sock, $addr) or die "Cannot bind socket: $!";

listen

Listens for incoming connections on a socket.

listen($sock, 5) or die "Cannot listen on socket: $!";

accept

Accepts an incoming connection on a socket.

my $client_addr = accept(my $client_sock, $sock);
print "Connection accepted\n";

shutdown

Shuts down a socket.

shutdown($sock, 2);  # 2 means shut down both reading and writing

---

53. Advanced Error Handling Functions

carp

Prints a warning message with a stack trace (from Carp module).

use Carp;
carp "This is a warning message\n";

cluck

Prints a warning message with a full stack trace (from Carp module).

use Carp;
cluck "This is a warning message\n";

eval (Advanced Usage)

Evaluates a block of code and catches errors.

eval {
    die "An error occurred\n";
};
if ($@) {
    print "Error caught: $@\n";
}

---

54. Advanced Regular Expression Functions

qr (Advanced Usage)

Compiles a regular expression with modifiers.

my $regex = qr/foo/i;  # Case-insensitive match
if ("FOO" =~ $regex) {
    print "Match found\n";  # Output: Match found
}

pos (Advanced Usage)

Sets the position of the last match.

my $str = "foo bar foo";
$str =~ /foo/g;
pos($str) = 4;
if ($str =~ /foo/g) {
    print "Match found at position ", pos($str), "\n";  # Output: Match found at position 8
}

study (Advanced Usage)

Optimizes a string for repeated pattern matching.

my $str = "Hello, World!";
study($str);
if ($str =~ /World/) {
    print "Match found\n";  # Output: Match found
}

---

55. Advanced Mathematical Functions

atan2 (Advanced Usage)

Returns the arctangent of Y/X in radians.

my $angle = atan2(1, 1);
print "Angle: $angle radians\n";  # Output: Angle: 0.785398163397448 radians

exp (Advanced Usage)

Returns the exponential of a number.

my $exp = exp(1);
print "Exponential: $exp\n";  # Output: Exponential: 2.71828182845905

log (Advanced Usage)

Returns the natural logarithm of a number.

my $log = log(10);
print "Natural Logarithm: $log\n";  # Output: Natural Logarithm: 2.30258509299405

sin (Advanced Usage)

Returns the sine of a number.

my $sin = sin(1);
print "Sine: $sin\n";  # Output: Sine: 0.841470984807897

cos (Advanced Usage)

Returns the cosine of a number.

my $cos = cos(1);
print "Cosine: $cos\n";  # Output: Cosine: 0.54030230586814

rand (Advanced Usage)

Generates a random number within a range.

my $rand_num = int(rand(100));
print "Random Number: $rand_num\n";  # Output: Random Number: [0, 99]

---

56. Advanced Miscellaneous Functions

tied (Advanced Usage)

Returns the object underlying a tied variable.

tie my %hash, 'Tie::Hash';
my $obj = tied %hash;
print "Tied Object: $obj\n";

untie (Advanced Usage)

Breaks the binding between a variable and a package.

untie %hash;

formline (Advanced Usage)

Formats a string (used with format).

formline("Hello, @<<<<", "World");
print $^A;  # Output: Hello, World

vec (Advanced Usage)

Treats a string as a vector of unsigned integers.

my $str = "ABC";
vec($str, 0, 8) = 88;
print "Modified String: $str\n";  # Output: Modified String: XBC

---

57. Advanced Special Variables

$^O

Returns the operating system name.

print "Operating System: $^O\n";  # Output: Operating System: linux (or darwin, MSWin32, etc.)

$^T

Returns the time the script started running.

print "Script Start Time: $^T\n";  # Output: Script Start Time: [epoch time]

$^X

Returns the name of the Perl executable.

print "Perl Executable: $^X\n";  # Output: Perl Executable: /usr/bin/perl

$^V

Returns the Perl version.

print "Perl Version: $^V\n";  # Output: Perl Version: v5.34.0 (or similar)

$^W

Returns the current value of the warning flag.

print "Warning Flag: $^W\n";  # Output: Warning Flag: 1 (if warnings are enabled)

---

58. Advanced File Test Operators

-M

Returns the age of the file in days since the script started.

my $age = -M 'file.txt';
print "File Age: $age days\n";

-C

Returns the inode change age of the file in days.

my $inode_age = -C 'file.txt';
print "Inode Change Age: $inode_age days\n";

-A

Returns the access age of the file in days.

my $access_age = -A 'file.txt';
print "Access Age: $access_age days\n";

59. Advanced Regular Expression Functions

study (Advanced Usage)

Optimizes a string for repeated pattern matching.

my $str = "Hello, World!";
study($str);
if ($str =~ /World/) {
    print "Match found\n";  # Output: Match found
}

pos (Advanced Usage)

Sets the position of the last match.

my $str = "foo bar foo";
$str =~ /foo/g;
pos($str) = 4;
if ($str =~ /foo/g) {
    print "Match found at position ", pos($str), "\n";  # Output: Match found at position 8
}

qr (Advanced Usage)

Compiles a regular expression with modifiers.

my $regex = qr/foo/i;  # Case-insensitive match
if ("FOO" =~ $regex) {
    print "Match found\n";  # Output: Match found
}

---

60. Advanced Mathematical Functions

atan2 (Advanced Usage)

Returns the arctangent of Y/X in radians.

my $angle = atan2(1, 1);
print "Angle: $angle radians\n";  # Output: Angle: 0.785398163397448 radians

exp (Advanced Usage)

Returns the exponential of a number.

my $exp = exp(1);
print "Exponential: $exp\n";  # Output: Exponential: 2.71828182845905

log (Advanced Usage)

Returns the natural logarithm of a number.

my $log = log(10);
print "Natural Logarithm: $log\n";  # Output: Natural Logarithm: 2.30258509299405

sin (Advanced Usage)

Returns the sine of a number.

my $sin = sin(1);
print "Sine: $sin\n";  # Output: Sine: 0.841470984807897

cos (Advanced Usage)

Returns the cosine of a number.

my $cos = cos(1);
print "Cosine: $cos\n";  # Output: Cosine: 0.54030230586814

rand (Advanced Usage)

Generates a random number within a range.

my $rand_num = int(rand(100));
print "Random Number: $rand_num\n";  # Output: Random Number: [0, 99]

---

61. Advanced Miscellaneous Functions

tied (Advanced Usage)

Returns the object underlying a tied variable.

tie my %hash, 'Tie::Hash';
my $obj = tied %hash;
print "Tied Object: $obj\n";

untie (Advanced Usage)

Breaks the binding between a variable and a package.

untie %hash;

formline (Advanced Usage)

Formats a string (used with format).

formline("Hello, @<<<<", "World");
print $^A;  # Output: Hello, World

vec (Advanced Usage)

Treats a string as a vector of unsigned integers.

my $str = "ABC";
vec($str, 0, 8) = 88;
print "Modified String: $str\n";  # Output: Modified String: XBC

---

62. Advanced Special Variables

$^O

Returns the operating system name.

print "Operating System: $^O\n";  # Output: Operating System: linux (or darwin, MSWin32, etc.)

$^T

Returns the time the script started running.

print "Script Start Time: $^T\n";  # Output: Script Start Time: [epoch time]

$^X

Returns the name of the Perl executable.

print "Perl Executable: $^X\n";  # Output: Perl Executable: /usr/bin/perl

$^V

Returns the Perl version.

print "Perl Version: $^V\n";  # Output: Perl Version: v5.34.0 (or similar)

$^W

Returns the current value of the warning flag.

print "Warning Flag: $^W\n";  # Output: Warning Flag: 1 (if warnings are enabled)

---

63. Advanced File Test Operators

-M

Returns the age of the file in days since the script started.

my $age = -M 'file.txt';
print "File Age: $age days\n";

-C

Returns the inode change age of the file in days.

my $inode_age = -C 'file.txt';
print "Inode Change Age: $inode_age days\n";

-A

Returns the access age of the file in days.

my $access_age = -A 'file.txt';
print "Access Age: $access_age days\n";

---

64. Advanced Input/Output Functions

sysread

Reads a fixed number of bytes from a filehandle.

open(my $fh, '<', 'file.txt') or die "Cannot open file: $!";
my $buffer;
sysread($fh, $buffer, 1024);
print "Read Data: $buffer\n";
close($fh);

syswrite

Writes a fixed number of bytes to a filehandle.

open(my $fh, '>', 'output.txt') or die "Cannot open file: $!";
syswrite($fh, "Hello, World!", 13);
close($fh);

fcntl

Performs low-level file control operations.

use Fcntl;
fcntl($fh, F_SETFL, O_NONBLOCK);

ioctl

Performs device-specific input/output operations.

use IO::Handle;
ioctl($fh, 0x1234, $arg);

---

65. Advanced System Interaction Functions

pipe

Creates a pair of filehandles for interprocess communication.

pipe(my $reader, my $writer);
print $writer "Hello, World!\n";
close($writer);
my $message = <$reader>;
print "Message: $message\n";  # Output: Message: Hello, World!
close($reader);

socket

Creates a socket for network communication.

use Socket;
socket(my $sock, PF_INET, SOCK_STREAM, getprotobyname('tcp'));

bind

Binds a socket to an address.

my $port = 12345;
my $addr = sockaddr_in($port, INADDR_ANY);
bind($sock, $addr) or die "Cannot bind socket: $!";

listen

Listens for incoming connections on a socket.

listen($sock, 5) or die "Cannot listen on socket: $!";

accept

Accepts an incoming connection on a socket.

my $client_addr = accept(my $client_sock, $sock);
print "Connection accepted\n";

shutdown

Shuts down a socket.

shutdown($sock, 2);  # 2 means shut down both reading and writing

---

66. Advanced Error Handling Functions

carp

Prints a warning message with a stack trace (from Carp module).

use Carp;
carp "This is a warning message\n";

cluck

Prints a warning message with a full stack trace (from Carp module).

use Carp;
cluck "This is a warning message\n";

eval (Advanced Usage)

Evaluates a block of code and catches errors.

eval {
    die "An error occurred\n";
};
if ($@) {
    print "Error caught: $@\n";
}

---

67. Advanced Regular Expression Functions

qr (Advanced Usage)

Compiles a regular expression with modifiers.

my $regex = qr/foo/i;  # Case-insensitive match
if ("FOO" =~ $regex) {
    print "Match found\n";  # Output: Match found
}

pos (Advanced Usage)

Sets the position of the last match.

my $str = "foo bar foo";
$str =~ /foo/g;
pos($str) = 4;
if ($str =~ /foo/g) {
    print "Match found at position ", pos($str), "\n";  # Output: Match found at position 8
}

study (Advanced Usage)

Optimizes a string for repeated pattern matching.

my $str = "Hello, World!";
study($str);
if ($str =~ /World/) {
    print "Match found\n";  # Output: Match found
}

---

68. Advanced Mathematical Functions

atan2 (Advanced Usage)

Returns the arctangent of Y/X in radians.

my $angle = atan2(1, 1);
print "Angle: $angle radians\n";  # Output: Angle: 0.785398163397448 radians

exp (Advanced Usage)

Returns the exponential of a number.

my $exp = exp(1);
print "Exponential: $exp\n";  # Output: Exponential: 2.71828182845905

log (Advanced Usage)

Returns the natural logarithm of a number.

my $log = log(10);
print "Natural Logarithm: $log\n";  # Output: Natural Logarithm: 2.30258509299405

sin (Advanced Usage)

Returns the sine of a number.

my $sin = sin(1);
print "Sine: $sin\n";  # Output: Sine: 0.841470984807897

cos (Advanced Usage)

Returns the cosine of a number.

my $cos = cos(1);
print "Cosine: $cos\n";  # Output: Cosine: 0.54030230586814

rand (Advanced Usage)

Generates a random number within a range.

my $rand_num = int(rand(100));
print "Random Number: $rand_num\n";  # Output: Random Number: [0, 99]

---

69. Advanced Miscellaneous Functions

tied (Advanced Usage)

Returns the object underlying a tied variable.

tie my %hash, 'Tie::Hash';
my $obj = tied %hash;
print "Tied Object: $obj\n";

untie (Advanced Usage)

Breaks the binding between a variable and a package.

untie %hash;

formline (Advanced Usage)

Formats a string (used with format).

formline("Hello, @<<<<", "World");
print $^A;  # Output: Hello, World

vec (Advanced Usage)

Treats a string as a vector of unsigned integers.

my $str = "ABC";
vec($str, 0, 8) = 88;
print "Modified String: $str\n";  # Output: Modified String: XBC

---

70. Advanced Special Variables

$^O

Returns the operating system name.

print "Operating System: $^O\n";  # Output: Operating System: linux (or darwin, MSWin32, etc.)

$^T

Returns the time the script started running.

print "Script Start Time: $^T\n";  # Output: Script Start Time: [epoch time]

$^X

Returns the name of the Perl executable.

print "Perl Executable: $^X\n";  # Output: Perl Executable: /usr/bin/perl

$^V

Returns the Perl version.

print "Perl Version: $^V\n";  # Output: Perl Version: v5.34.0 (or similar)

$^W

Returns the current value of the warning flag.

print "Warning Flag: $^W\n";  # Output: Warning Flag: 1 (if warnings are enabled)

---

71. Advanced File Test Operators

-M

Returns the age of the file in days since the script started.

my $age = -M 'file.txt';
print "File Age: $age days\n";

-C

Returns the inode change age of the file in days.

my $inode_age = -C 'file.txt';
print "Inode Change Age: $inode_age days\n";

-A

Returns the access age of the file in days.

my $access_age = -A 'file.txt';
print "Access Age: $access_age days\n";

---