Python string function vs PHP string function

php_string.php

<?php
$parrot = "Norwegian Blue";
echo strlen($parrot);
echo strtolower($parrot);
echo strtoupper($parrot);

$pi = 3.14
echo $pi;

if(is_string($pi)): 
	echo "string";
else:
	echo "not a string";
endif;

python_string.py

parrot = "Norwegian Blue"
print len(parrot)
print parrot.lower()
print parrot.upper()

pi = 3.14
print str(pi) #in Python you need to convert number to string in order to print it out


original = raw_input("Enter a word:")
## the function isalpha() which returns False since the string contains non-letter characters.
if len(original) > 0 and original.isalpha():
    print original
else:
    print "empty"

ruby_string.rb

print "Please input somethings:"
user_input = gets.chomp

temp = user_input.to_i

if temp.is_a?(String)
  print "string"
else
  print "is not a string"
end

if user_input.empty?
    print "Please enter a non empty string:"
    user_input = gets.chomp
end 

user_input.downcase!

if user_input.include? "s"
    user_input.gsub!(/s/,"th")
    puts "#{user_input}"
else
    print user_input
end