php functions on strings

The following are some functions which can be used on strings in php.

1. str_word_count :- str_word_count has different results depending on parameters.
• str_word_count($string_variable) returns the word count
• str_word_count($string_variable, (0,1 or 2)) where
• 0 returns the word count(the default option)
• 1 returns an array
• 2 returns an associative array
• str_word_count($string_variable, (0,1,2), ' (something to be included as a word for ex '.!&' ').
• different arguments included next to each other.
2. str_shuffle($string_variable) :- shuffles string_variable
3. substr($string_variable,  starting position, ending position) :- returns the substring
4. strlen($string_variable) :- returns the length of the string_variable
5. strtolower($string_variable) :- returns $string_variable with all characters in lower case
6. strttoupper($string_variable) :- returns $string_variable with all characters in upper case