Perl | String functions (length, lc, uc, index, rindex)

String in Perl is a sequence of character enclosed within some kinds of quotation marks. Perl string can contain UNICODE, ASCII and escape sequence characters. Perl provides the various function to manipulate the string like any other programming language. Some string functions of Perl are as follows:

• length()
• lc()
• uc()
• index()
• rindex()

length(): This function is used to find the number of characters in a string. This function returns the length of the string. Below are the programs to illustrate this method.

• Example 1:

  # Perl program to demonstrate
  # string length function
  
  # string
  my $s = "geeksforgeeks";
  
  # using length function &
  # displaying length
  print(length($s),"\n");

  Output:

  13
  

• Example 2:

  # Perl program to demonstrate
  # string length function
  
  # string
  my $s = "#$%HeLLo CSHARP &+#*";
  
  # using length function &
  # displaying length
  print(length($s),"\n");

  Output:

  19
  

lc(): This function return the lower case version of a string. Below are the programs to illustrate this method.

• Example 1:

  # Perl program to demonstrate
  # string lc function
  
  # string
  my $s = "GEEKSFORGEEKS\n";
  
  # using lc function &
  # displaying result
  print("To lower case: ");
  print(lc($s),"\n");

  Output:

  To lower case: geeksforgeeks
  

• Example 2:

  # Perl program to demonstrate
  # string lc function
  
  # string
  my $s = "GEEKS\n";
  
  # using lc function &
  # displaying result
  print("To lower case: ");
  print(lc($s),"\n");

  Output:

  To lower case: geeks
  

uc(): This function return the upper case version of a string. Below are the programs to illustrate this method.

• Example 1:

  # Perl program to demonstrate
  # string uc function
  
  # string
  my $s = "geeksforgeeks";
  
  # using uc function &
  # displaying result
  print("To Upper Case: ");
  print(uc($s),"\n");

  Output:

  To Upper Case: GEEKSFORGEEKS
  

• Example 2:

  # Perl program to demonstrate
  # string uc function
  
  # string
  my $s = "GeekS\n";
  
  # using uc function &
  # displaying result
  print("To Upper Case: ");
  print(uc($s),"\n");

  Output:

  To Upper Case: GEEKS
  

index(): This method will search a substring from a specified position in a string and returns the position of the first occurrence of the substring in the string. If the position is omitted, it will search from the beginning of the string. This method will take the two parameters i.e. the original string and the substring that has to be searched.

Example :

# Perl Program to illustrate
# the index() function

# !/usr/bin/perl
use warnings;
use strict;

# string
my $st = "GeeksforGeeks\n";

# substring
my $subs = "for";

# using index function
my $r = index($st, $subs);

# displaying result
print(qq\The substring $subs found at position $r in string $st\);

Output:

The substring for found at position 5 in string GeeksforGeeks

rindex() This function is same as index() except it returns the last occurrence of text in a string. Also, a third parameter can be given which returns position before or at that location. It searches from the end of the string instead of from the beginning. Below are the programs to illustrate this method.

Example 1:

# Perl Program to illustrate
# the rindex() function

# !/usr/bin/perl
use warnings;
use strict;

# string
my $st = "GeeksforGeeks\n";

# substring
my $subs = "for";

# using rindex function
my $r = rindex($st, $subs);

# displaying result
print(qq\The substring $subs found at position $r in string $st\);

Output:

The substring for found at position 5 in string GeeksforGeeks

Example 2:

# Perl Program to illustrate
# the rindex() function with
# three parameters

# !/usr/bin/perl

# using rindex() function
$p = rindex("GeeksForGFGGeeksgeeksforGFG", "GFG");

print "Founded position of GFG $p\n";

# Use the first position found
# as the offset to the next search.
# The length of the target string
# is subtracted from the offset
# to save time.
$p = rindex("GeeksForGFGGeeksgeeksforGFG", "GFG", $p-7);
print "Founded position of GFG $p\n";

Output:

Founded position of GFG 24
Founded position of GFG 8