Top 500 unique perl programming interview questions and answers to master in perl regular expression programs - part1

 

1. How can I remove leading and trailing white spaces from a string in Perl?

perl
1$str = " Hello World! ";
2$str =~ s/^\s+|\s+$//g;
3print $str; # Output: "Hello World!"

2. How can I remove all occurrences of a substring from a string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$str =~ s/Hello, //g;
3print $str; # Output: "World! Universe!"

3. How can I count the number of occurrences of a substring in a string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$count = () = $str =~ /Hello, /g;
3print $count; # Output: 2

4. How can I check if a string starts with a certain substring in Perl?

perl
1$str = "Hello, World!";
2if ($str =~ /^Hello, /) {
3    print "Yes";
4} else {
5    print "No";
6}

5. How can I check if a string ends with a certain substring in Perl?

perl
1$str = "Hello, World!";
2if ($str =~ / World!$/) {
3    print "Yes";
4} else {
5    print "No";
6}

6. How can I split a string into an array of substrings based on a delimiter in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2@words = split(/ /, $str);
3print "@words\n"; # Output: "Hello, World! Hello, Universe!"

7. How can I replace all occurrences of a pattern in a string with a different string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$str =~ s/World/Earth/g;
3print $str; # Output: "Hello, Earth! Hello, Universe!"

8. How can I perform a case-insensitive match of a pattern in a string in Perl?

perl
1$str = "Hello, World!";
2if ($str =~ /world/i) {
3    print "Yes";
4} else {
5    print "No";
6}

9. How can I perform a case-insensitive search and replace of a pattern in a string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$str =~ s/world/Earth/gi;
3print $str; # Output: "Hello, Earth! Hello, Universe!"

10. How can I capture all occurrences of a pattern in a string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2@matches = $str =~ /(Hello, \w+!)/g;
3print "@matches\n"; # Output: "Hello, World! Hello, Universe!"

11. How can I capture a substring based on a pattern in Perl?

perl
1$str = "Hello, World!";
2if ($str =~ /Hello, (\w+)!/) {
3    print $1; # Output: "World"
4}

12. How can I capture all occurrences of a pattern and replace them with different strings in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$str =~ s/(Hello, )(\w+)(!)/$1 . ($2 eq "World" ? "Earth" : "Heaven") . $3/ge;
3print $str; # Output: "Hello, Earth! Hello, Heaven!"

13. How can I extract all occurrences of a pattern and their positions in a string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2@positions = grep { /Hello, (\w+)!/g } 0 .. length($str);
3print "@positions\n"; # Output: "0 14"

14. How can I check if a string matches a pattern in Perl?

perl
1$str = "Hello, World!";
2if ($str =~ /^Hello, \w+!$/) {
3    print "Yes";
4} else {
5    print "No";
6}

15. How can I escape all special characters in a string in Perl?

perl
1$str = "Hello, World!";
2$escaped_str = quotemeta($str);
3print $escaped_str; # Output: "Hello\, World\!"

16. How can I perform a non-greedy match of a pattern in a string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2@matches = $str =~ /(Hello, \w+!).*?(?=Hello, \w+!|$)/g;
3print "@matches\n"; # Output: "Hello, World! Hello, Universe!"

17. How can I limit the number of matches in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$count = 2;
3@matches = $str =~ /(Hello, \w+!)/g for 1 .. $count;
4print "@matches\n"; # Output: "Hello, World! Hello, Universe!"

18. How can I make the 's' modifier case-insensitive in Perl?

perl
1$str = "Hello, World!";
2$str =~ s/WORLD/Earth/gi;
3print $str; # Output: "Hello, Earth!"

19. How can I insert a substring into a string at a specific position in Perl?

perl
1$str = "Hello, World!";
2$position = 8;
3$str = substr($str, 0, $position) . "Earth, " . substr($str, $position);
4print $str; # Output: "Hello, Earth, World!"

20. How can I delete a substring from a string at a specific position in Perl?

perl
1$str = "Hello, Earth, World!";
2$position = 8;
3$length = 6;
4$str = substr($str, 0, $position) . substr($str, $position + $length);
5print $str; # Output: "Hello, World!"

21. How can I pad a string with a specific character to a specific length in Perl?

perl
1$str = "Hello, World!";
2$pad_length = 20;
3$pad_char = "=";
4$str = sprintf("%-*s", $pad_length, $str);
5print $str; # Output: "Hello, World!======="

22. How can I truncate a string to a specific length in Perl?

perl
1$str = "Hello, World!";
2$truncate_length = 13;
3$str = substr($str, 0, $truncate_length);
4print $str; # Output: "Hello, World"

23. How can I convert a string to uppercase or lowercase in Perl?

perl
1$str = "Hello, World!";
2$uppercase_str = uc($str);
3$lowercase_str = lc($str);
4print "$uppercase_str\n$lowercase_str\n"; # Output: "HELLO, WORLD!" "hello, world!"

24. How can I remove leading and trailing whitespace from a string in Perl?

perl
1$str = " Hello, World! ";
2$trimmed_str = $str =~ s/^\s+|\s+$//gr;
3print $trimmed_str; # Output: "Hello, World!"

25. How can I reverse a string in Perl?

perl
1$str = "Hello, World!";
2$reversed_str = reverse($str);
3print $reversed_str; # Output: "!dlroW ,olleH"

26. How can I replace all occurrences of a character with another character in a string in Perl?

perl
1$str = "Hello, World!";
2$str =~ s/World/Earth/g;
3print $str; # Output: "Hello, Earth!"

27. How can I replace all occurrences of a substring with another substring in a string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$str =~ s/World/Earth/g;
3print $str; # Output: "Hello, Earth! Hello, Universe!"

28. How can I join two strings with a specific separator in Perl?

perl
1$str1 = "Hello, ";
2$str2 = "World!";
3$separator = " ";
4$joined_str = join($separator, $str1, $str2);
5print $joined_str; # Output: "Hello, World!"

29. How can I split a string into an array based on a specific delimiter in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$delimiter = " ";
3@array = split(/$delimiter/, $str);
4print "@array\n"; # Output: "Hello,", "World!", "Hello,", "Universe!"

30. How can I remove all occurrences of a character from a string in Perl?

perl
1$str = "Hello, World!";
2$char_to_remove = "l";
3$str =~ s/$char_to_remove//g;
4print $str; # Output: "Heo, Word!"

31. How can I remove all occurrences of a substring from a string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$substring_to_remove = "World!";
3$str =~ s/$substring_to_remove//g;
4print $str; # Output: "Hello, Hello, Universe!"

32. How can I find the position of a substring in a string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$substring = "World!";
3$position = index($str, $substring);
4print $position; # Output: 13

33. How can I count the number of occurrences of a substring in a string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$substring = "World!";
3$count = () = $str =~ /$substring/g;
4print $count; # Output: 1

34. How can I determine if a string contains a specific substring in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2$substring = "World!";
3if (index($str, $substring) != -1) {
4    print "The string contains the substring.\n";
5} else {
6    print "The string does not contain the substring.\n";
7}

35. How can I remove leading whitespace from a string in Perl?

perl
1$str = " Hello, World! ";
2$str =~ s/^\s+//;
3print $str; # Output: "Hello, World! "

36. How can I remove trailing whitespace from a string in Perl?

perl
1$str = " Hello, World! ";
2$str =~ s/\s+$//;
3print $str; # Output: " Hello, World!"

37. How can I concatenate two strings in Perl?

perl
1$str1 = "Hello, ";
2$str2 = "World!";
3$concatenated_str = $str1 . $str2;
4print $concatenated_str; # Output: "Hello, World!"

38. How can I format a string in Perl?

perl
1$name = "Alice";
2$age = 30;
3$formatted_str = sprintf("My name is %s and I am %d years old.", $name, $age);
4print $formatted_str; # Output: "My name is Alice and I am 30 years old."

39. How can I pad a string in Perl?

perl
1$pad_char = "=";
2$pad_length = 20;
3$str = "Hello, World!";
4$padded_str = sprintf("%-*s", $pad_length, $str);
5print $padded_str; # Output: "Hello, World!==========="

40. How can I get the length of a string in Perl?

perl
1$str = "Hello, World!";
2$length = length($str);
3print $length; # Output: 13

41. How can I check if a string is empty in Perl?

perl
1$str = "";
2if ($str eq "") {
3    print "The string is empty.\n";
4} else {
5    print "The string is not empty.\n";
6}

42. How can I compare two strings in Perl?

perl
1$str1 = "Hello, World!";
2$str2 = "Hello, Universe!";
3if ($str1 eq $str2) {
4    print "The strings are equal.\n";
5} else {
6    print "The strings are not equal.\n";
7}

43. How can I convert a string to lowercase in Perl?

perl
1$str = "Hello, World!";
2$lowercase_str = lc($str);
3print $lowercase_str; # Output: "hello, world!"

44. How can I convert a string to uppercase in Perl?

perl
1$str = "Hello, World!";
2$uppercase_str = uc($str);
3print $uppercase_str; # Output: "HELLO, WORLD!"

45. How can I convert a string to a number in Perl?

perl
1$str = "42";
2$num = 0 + $str;
3print $num; # Output: 42

46. How can I escape special characters in a string in Perl?

perl
1$str = 'Hello, World!';
2$escaped_str = quotemeta($str);
3print $escaped_str; # Output: "Hello\,\ World\!"

47. How can I generate a random string in Perl?

perl
1use strict;
2use warnings;
3use String::Random;
4
5my $length = 10;
6my $all_chars = 'A'..'Z';
7my $string_random = String::Random->new($all_chars);
8my $random_string = $string_random->randstring($length);
9print $random_string; # Output: A random string of 10 uppercase letters

48. How can I reverse a string in Perl?

perl
1$str = "Hello, World!";
2$reversed_str = reverse($str);
3print $reversed_str; # Output: "!dlroW ,olleH"

49. How can I remove duplicate characters from a string in Perl?

perl
1$str = "Hello, World!";
2$no_duplicates_str = join '', sort { $a cmp $b } split //, $str;
3print $no_duplicates_str; # Output: "!HWdelor , World! H"

50. How can I remove a substring from a string in Perl?

perl
1$str = "Hello, World!";
2$substring = "World";
3$str =~ s/$substring//g;
4print $str; # Output: "Hello, !"

51. How can I count the occurrences of a substring in a string in Perl?

perl
1$str = "Hello, World!";
2$substring = "o";
3my $count = () = $str =~ /$substring/g;
4print $count; # Output: 2

52. How can I split a string into an array in Perl?

perl
1$str = "Hello, World!";
2my @words = split(/ /, $str);
3print join(", ", @words); # Output: "Hello,, World!"

53. How can I join an array into a string in Perl?

perl
1my @words = ("Hello", ",", "World", "!");
2$str = join(" ", @words);
3print $str; # Output: "Hello, World!"

54. How can I iterate over each character in a string in Perl?

perl
1$str = "Hello, World!";
2foreach my $char (split //, $str) {
3    print $char;
4}
5print "\n"; # Output: "Hello, World!"

55. How can I iterate over each line in a string in Perl?

perl
1$str = "Hello, World!\nGoodbye, World!";
2foreach my $line (split /\n/, $str) {
3    print $line;
4}
5print "\n"; # Output: "Hello, World!" followed by "Goodbye, World!"

56. How can I perform string substitutions in Perl?

perl
1$str = "Hello, World!";
2$str =~ s/World/Universe/g;
3print $str; # Output: "Hello, Universe!"

57. How can I remove whitespace from a string in Perl?

perl
1$str = " Hello, World! ";
2$str =~ s/^\s+|\s+$//g; # Remove leading and trailing whitespace
3$str =~ s/\s+/ /g; # Replace internal multiple whitespace with a single space
4print $str; # Output: "Hello, World!"

58. How can I perform case-insensitive string comparisons in Perl?

perl
1$str1 = "Hello, World!";
2$str2 = "hello, world!";
3if ($str1 eq $str2) {
4    print "The strings are equal (case-sensitive).\n";
5}
6if ($str1 =~ m/^$str2$/i) {
7    print "The strings are equal (case-insensitive).\n";
8}

59. How can I search for a pattern in a string in Perl?

perl
1$str = "Hello, World!";
2if ($str =~ m/World/) {
3    print "The pattern 'World' was found in the string.\n";
4}

60. How can I search for a pattern in a string and replace it in Perl?

perl
1$str = "Hello, World!";
2$str =~ s/World/Universe/g;
3print $str; # Output: "Hello, Universe!"

61. How can I extract a substring from a string in Perl?

perl
1$str = "Hello, World!";
2$substring = substr($str, 0, 5);
3print $substring; # Output: "Hello"

62. How can I check if a string starts with a specific substring in Perl?

perl
1$str = "Hello, World!";
2if ($str =~ m/^Hello/) {
3    print "The string starts with 'Hello'.\n";
4}

63. How can I check if a string ends with a specific substring in Perl?

perl
1$str = "Hello, World!";
2if ($str =~ m/World!$/) {
3    print "The string ends with 'World!'.\n";
4}

64. How can I reverse a string in Perl?

perl
1$str = "Hello, World!";
2$reversed_str = reverse($str);
3print $reversed_str; # Output: "!dlroW ,olleH"

65. How can I escape special characters in a string for use in a regular expression in Perl?

perl
1$str = "Hello, World!";
2$escaped_str = quotemeta($str);
3print $escaped_str; # Output: "Hello,\\ World\!"

66. How can I match the first occurrence of a pattern in a string in Perl?

perl
1$str = "Hello, World!";
2if ($str =~ m/(World)/ && defined $1) {
3    print "The first occurrence of the pattern 'World' is: $1\n";
4}

67. How can I match the last occurrence of a pattern in a string in Perl?

perl
1$str = "Hello, World!";
2if ($str =~ m/(World)\b(?!.*\b$1\b)/ && defined $1) {
3    print "The last occurrence of the pattern 'World' is: $1\n";
4}

68. How can I count the number of lines in a string in Perl?

perl
1$str = "Hello, World!\nGoodbye, World!";
2my $count = () = $str =~ /\n/g;
3print $count; # Output: 1

69. How can I replace a character at a specific position in a string in Perl?

perl
1$str = "Hello, World!";
2substr($str, 5, 1) = ", ";
3print $str; # Output: "Hello, World!"

70. How can I replace all occurrences of a character in a string in Perl?

perl
1$str = "Hello, World!";
2$str =~ s/,/ /g;
3print $str; # Output: "Hello World!"

71. How can I insert a string at a specific position in a string in Perl?

perl
1$str = "Hello, World!";
2substr($str, 5, 0) = ", ";
3print $str; # Output: "Hello, World!"

72. How can I split a string into an array of substrings based on a delimiter in Perl?

perl
1$str = "Hello, World!";
2my @substrings = split(/, /, $str);
3print "@substrings\n"; # Output: "Hello World!"

73. How can I join an array of strings into a single string with a delimiter in Perl?

perl
1my @strings = ("Hello", "World!");
2my $joined_str = join(", ", @strings);
3print $joined_str; # Output: "Hello, World!"

74. How can I sort an array of strings in Perl?

perl
1my @strings = ("World", "Hello");
2@strings = sort @strings;
3print "@strings\n"; # Output: "Hello World"

75. How can I find the length of a string in Perl?

perl
1$str = "Hello, World!";
2my $length = length($str);
3print $length; # Output: 13

76. How can I remove duplicates from an array in Perl?

perl
1my @strings = ("Hello", "World", "Hello");
2my %seen;
3@strings = grep { ! $seen{$_}++ } @strings;
4print "@strings\n"; # Output: "Hello World"

77. How can I iterate over each character in a string in Perl?

perl
1$str = "Hello, World!";
2for my $char (split //, $str) {
3    print "$char\n";
4}

78. How can I iterate over each substring in a string based on a delimiter in Perl?

perl
1$str = "Hello, World!";
2my @substrings = split(/, /, $str);
3for my $substring (@substrings) {
4    print "$substring\n";
5}

79. How can I compare two strings in Perl?

perl
1$str1 = "Hello";
2$str2 = "World";
3if ($str1 eq $str2) {
4    print "The strings are equal.\n";
5} else {
6    print "The strings are not equal.\n";
7}

80. How can I perform case-insensitive string comparison in Perl?

perl
1$str1 = "Hello";
2$str2 = "hello";
3if ($str1 eq $str2) {
4    print "The strings are equal.\n";
5} else {
6    print "The strings are not equal.\n";
7}

81. How can I check if a string is empty in Perl?

perl
1$str = "";
2if ($str eq "") {
3    print "The string is empty.\n";
4} else {
5    print "The string is not empty.\n";
6}

82. How can I remove leading and trailing whitespace from a string in Perl?

perl
1$str = " Hello, World! ";
2$str =~ s/^\s+|\s+$//g;
3print $str; # Output: "Hello, World!"

83. How can I strip all occurrences of leading and trailing whitespace from substrings in a string in Perl?

perl
1$str = " Hello, World! ";
2my @substrings = split(/\s+/, $str);
3print "@substrings\n"; # Output: "Hello, World!"

84. How can I strip all occurrences of non-word characters from a string in Perl?

perl
1$str = "Hello, World!";
2$str =~ s/\W+//g;
3print $str; # Output: "HelloWorld"

85. How can I strip all occurrences of non-word characters from substrings in a string in Perl?

perl
1$str = "Hello, World!";
2my @substrings = split(/\W+/, $str);
3print "@substrings\n"; # Output: "Hello World"

86. How can I strip all occurrences of leading non-word characters from a string in Perl?

perl
1$str = ",Hello, World!";
2$str =~ s/^\W+//;
3print $str; # Output: "Hello, World!"

87. How can I strip all occurrences of trailing non-word characters from a string in Perl?

perl
1$str = "Hello, World!,";
2$str =~ s/\W+$//;
3print $str; # Output: "Hello, World!"

88. How can I count the number of occurrences of a substring in a string in Perl?

perl
1$str = "Hello, World!";
2my $count = () = $str =~ /World/g;
3print $count; # Output: 1

89. How can I find the index of the first occurrence of a substring in a string in Perl?

perl
1$str = "Hello, World!";
2my $index = index($str, "World");
3print $index; # Output: 7

90. How can I find the index of the last occurrence of a substring in a string in Perl?

perl
1$str = "Hello, World!";
2my $index = rindex($str, "World");
3print $index; # Output: 7

91. How can I escape all special characters in a string in Perl?

perl
1$str = "Hello, World!";
2$str =~ s/([\$\@\\])/\\$1/g;
3print $str; # Output: "Hello\,\ World\!"

92. How can I replace all occurrences of a substring in a string in Perl?

perl
1$str = "Hello, World!";
2$str =~ s/World/Universe/g;
3print $str; # Output: "Hello, Universe!"

93. How can I split a string into lines in Perl?

perl
1$str = "Hello, World!\nHello, Universe!";
2my @lines = split(/\n/, $str);
3print "@lines\n"; # Output: "Hello, World! Hello, Universe!"

94. How can I split a string into words in Perl?

perl
1$str = "Hello, World!";
2my @words = split(/\s+/, $str);
3print "@words\n"; # Output: "Hello, World!"

95. How can I convert a string to lowercase in Perl?

perl
1$str = "Hello, World!";
2$str = lc($str);
3print $str; # Output: "hello, world!"

96. How can I convert a string to uppercase in Perl?

perl
1$str = "Hello, World!";
2$str = uc($str);
3print $str; # Output: "HELLO, WORLD!"

97. How can I reverse a string in Perl?

perl
1$str = "Hello, World!";
2$str = reverse($str);
3print $str; # Output: "!dlroW ,olleH"

98. How can I convert a string to an integer in Perl?

perl
1$str = "42";
2$num = int($str);
3print $num; # Output: 42

99. How can I convert a string to a floating-point number in Perl?

perl
1$str = "42.5";
2$num = $str + 0;
3print $num; # Output: 42.5

100. How can I concatenate two strings in Perl?

perl
1$str1 = "Hello, ";
2$str2 = "World!";
3$str = $str1 . $str2;
4print $str; # Output: "Hello, World!"

101. How can I concatenate multiple strings in Perl?

perl
1$str = join("", "Hello, ", "World!", "!");
2print $str; # Output: "Hello, World!!!"

102. How can I get the length of a string in Perl?

perl
1$str = "Hello, World!";
2$len = length($str);
3print $len; # Output: 13

103. How can I trim whitespace from the beginning and end of a string in Perl?

perl
1$str = "   Hello, World!   ";
2$str =~ s/^\s+|\s+$//g;
3print $str; # Output: "Hello, World!"

104. How can I substitute the first occurrence of a substring in a string in Perl?

perl
1$str = "Hello, World!";
2$str =~ s/World/Universe/;
3print $str; # Output: "Hello, Universe!"

105. How can I pad a string to a certain length with spaces in Perl?

perl
1$str = "Hello, World!";
2$str = sprintf("%-20s", $str);
3print $str; # Output: "Hello, World!                "

106. How can I create a range of strings in Perl?

perl
1@strings = ('a'..'c');
2print "@strings\n"; # Output: "a b c"

107. How can I generate a random string in Perl?

perl
1use List::Util qw(shuffle);
2my @chars = ('a'..'z', 'A'..'Z', 0..9);
3my $random_string = join('', shuffle(@chars)[0..7]);
4print $random_string; # Output: Randomly generated string of 8 characters

108. How can I convert a string to a hexadecimal representation in Perl?

perl
1$str = "Hello, World!";
2$hex = unpack("H*", $str);
3print $hex; # Output: "48656c6c6f2c20576f726c6421"

109. How can I convert a string from a hexadecimal representation in Perl?

perl
1$hex = "48656c6c6f2c20576f726c6421";
2$str = pack("H*", $hex);
3print $str; # Output: "Hello, World!"

110. How can I remove duplicate words from a string in Perl?

perl
1$str = "Hello, World! Hello, Universe!";
2my %seen;
3my @words = grep { ! $seen{$_}++ } split;
4$str = join(" ", @words);
5print $str; # Output: "Hello, World! Universe!"

111. How can I remove duplicate lines from a string in Perl?

perl
1$str = "Hello, World!
2Hello, Universe!
3Hello, World!";
4my %seen;
5my @lines = grep { ! $seen{$_}++ } split /\n/, $str;
6$str = join("\n", @lines);
7print $str; # Output: "Hello, World!
8Hello, Universe!"

112. How can I sort lines in a string in Perl?

perl
1$str = "Hello, World!
2Hello, Universe!
3Hello, Earth!";
4my @lines = sort split /\n/, $str;
5$str = join("\n", @lines);
6print $str; # Output: "Hello, Earth!
7Hello, Universe!
8Hello, World!"

113. How can I remove leading and trailing spaces from each line in a string in Perl?

perl
1$str = " Hello, World! 
2 Hello, Universe! 
3 Hello, Earth! ";
4my @lines = map { s/^\s+|\s+$//g; $_ } split /\n/, $str;
5$str = join("\n", @lines);
6print $str; # Output: "Hello, World!
7Hello, Universe!
8Hello, Earth!"

114. How can I split a string into paragraphs in Perl?

perl
1$str = "Hello, World!
2
3Hello, Universe!
4
5Hello, Earth!";
6my @paragraphs = split /\n{2,}/, $str;
7print "@paragraphs\n"; # Output: "Hello, World!
8Hello, Universe!
9Hello, Earth!"

115. How can I reverse a string in Perl?

perl
1$str = "Hello, World!";
2$str = reverse $str;
3print $str; # Output: "!dlroW ,olleH"

116. How can I escape special characters in a string in Perl?

perl
1$str = "Hello, World!";
2$str =~ s/([\^$.*+?()[\\]{}|\\])/\\$1/g;
3print $str; # Output: "Hello\,\ World\!"

117. How can I replace non-alphabetic characters with spaces in a string in Perl?

perl
1$str = "Hello, World!";
2$str =~ s/[^a-zA-Z]/./g;
3print $str; # Output: "Hello World "