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String functions in Perl

In Perl, string manipulation is a fundamental aspect of the language, given its roots in text processing. Perl provides a rich set of functions for string operations. This tutorial provides an overview of the essential string functions in Perl.

1. String Length: length

Returns the length of a string.

my $str = "Hello, world!";
my $len = length($str);  # $len is 13

2. Concatenation: .

Combine two strings.

my $greeting = "Hello, " . "world!";  # "Hello, world!"

3. String Repetition: x

Repeats a string a given number of times.

my $repeated = "ha" x 3;  # "hahaha"

4. Substring Extraction: substr

Extracts part of a string.

my $extract = substr("Hello, world!", 0, 5);  # "Hello"

You can also use substr to modify parts of a string.

substr($str, 7, 5) = "Planet";  # $str is now "Hello, Planet!"

5. Case Conversion: lc, uc, lcfirst, and ucfirst

  • lc: Convert to lowercase.
  • uc: Convert to uppercase.
  • lcfirst: Convert the first character to lowercase.
  • ucfirst: Convert the first character to uppercase.
print lc("HELLO");       # "hello"
print uc("world");       # "WORLD"
print ucfirst("hello");  # "Hello"
print lcfirst("WORLD");  # "wORLD"

6. String Indexing: index and rindex

  • index: Find the position of a substring.
  • rindex: Find the last position of a substring.
my $position = index("apple pie", "pie");   # 6
my $last_pos = rindex("apple pie pie", "pie");  # 10

7. String Replace: Using the s/// operator

Replace parts of a string using regular expressions.

my $text = "Hello, world!";
$text =~ s/world/Perl/;  # $text is now "Hello, Perl!"

8. String Split and Join: split and join

  • split: Breaks a string into a list of substrings.
  • join: Combines a list of strings into a single string.
my @words = split(/ /, "Hello, world!");
my $sentence = join(" ", @words);

9. Quoting Strings: q and qq

  • q: Single quote a string.
  • qq: Double quote a string.
my $single = q(This is a 'single' quoted string);
my $double = qq(This is a "double" quoted string);

10. String Chomp and Chop: chomp and chop

  • chomp: Removes trailing newline or a specific trailing string.
  • chop: Removes the last character from a string.
my $input = "Hello\n";
chomp($input);  # $input is now "Hello"

my $word = "Hello";
chop($word);    # $word is now "Hell"

11. Formatting Strings: printf and sprintf

Format strings with specific layouts.

printf("I have %d apples.", 5);  # Prints "I have 5 apples."

my $formatted = sprintf("I have %d apples.", 5);  # "I have 5 apples."

12. Summary

Perl's rich set of string functions makes it a powerful language for text processing tasks. By mastering these functions, you can efficiently manipulate, format, and analyze textual data in your Perl programs.

  1. Manipulating strings in Perl:

    • Description: Basic string manipulation operations.
    • Code Example:
      my $string = "Hello, Perl!";

# Manipulating strings
my $uppercase = uc($string);
my $lowercase = lc($string);

  2. String concatenation in Perl:

    • Description: Concatenating strings using the concatenation operator (.).
    • Code Example:
      my $first_name = "John";
my $last_name = "Doe";

my $full_name = $first_name . " " . $last_name;

  3. Substring extraction in Perl:

    • Description: Extracting substrings using substr.
    • Code Example:
      my $sentence = "Perl is powerful";

my $substring = substr($sentence, 5, 2);  # Extracts "is"

  4. String length function in Perl:

    • Description: Determining the length of a string using length.
    • Code Example:
      my $word = "Perl";

my $length = length($word);

  5. String comparison in Perl:

    • Description: Comparing strings using eq, ne, lt, le, gt, ge.
    • Code Example:
      my $str1 = "Perl";
my $str2 = "Python";

if ($str1 eq $str2) {
    print "Strings are equal.\n";
} else {
    print "Strings are not equal.\n";
}

  6. Searching and replacing in strings in Perl:

    • Description: Searching and replacing using index and s///.
    • Code Example:
      my $sentence = "Perl is fun and Perl is powerful";

# Searching for a substring
my $position = index($sentence, "Perl");

# Replacing a substring
$sentence =~ s/Perl/Python/;

  7. String splitting and joining in Perl:

    • Description: Splitting and joining strings using split and join.
    • Code Example:
      my $csv_data = "John,Doe,30";

# Splitting a CSV string
my @fields = split(',', $csv_data);

# Joining array elements into a string
my $joined_data = join('-', @fields);

  8. Regular expressions for string manipulation in Perl:

    • Description: Using regular expressions for advanced string manipulation.
    • Code Example:
      my $text = "The quick brown fox jumps over the lazy dog";

# Matching words starting with 'b'
my @matches = $text =~ /\b[bB]\w+/g;

  9. Case conversion functions in Perl strings:

    • Description: Converting string case using ucfirst, lcfirst, uc, lc.
    • Code Example:
      my $name = "alice";

# Capitalizing the first letter
my $capitalized = ucfirst($name);

# Converting to uppercase
my $uppercase_name = uc($name);
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