- strcmp
 - strcasecmp
 - explode
 - implode
 - nl2br
 - file_get_contents
 - str_replace
 - iconv
 - urlencode
 
String functions
There are lots of string functions in PHP. Here are a few examples:
- strcmp - compare two string returns, -1, 0 +1 based on order according to ASCII table
 - strcasecmp
 - explode - split string to elements and return an array
 - implode - join array to make a string
 - nl2br - new line to html-break
 - file_get_contents - read in a whole file without explicitely opening (slurp)
 - str_replace - replace characters in a string
 - iconv - convert between character encodings: iconv('ISO-8859-8', 'UTF-8', $str)
 - urlencode - when we are generating URLs some characters (e.g. space) need to be encoded